[PATCH v3 0/8] media: Introduce V4L2 extensible parameters

[PATCH v3 0/8] media: Introduce V4L2 extensible parameters

[Jacopo Mondi]

Extensible parameters meta formats have been introduced in the Linux
kernel v6.12 initially to support different revision of the RkISP1 ISP
implemented in different SoC. In order to avoid breaking userspace
everytime an ISP configuration block is added or modified in the uAPI
these new formats, which are versionated and extensible by their
definition have been introduced.

See for reference:
e9d05e9d5db1 ("media: uapi: rkisp1-config: Add extensible params format")
6c53a7b68c5d ("media: rkisp1: Implement extensible params support")

The Amlogic C3 ISP driver followed shortly, introducing an extensible
format for the ISP configuration:

6d406187ebc0 ("media: uapi: Add stats info and parameters buffer for C3 ISP")

with a very similar, if not identical, implementation of the routines to
validate and handle the ISP configuration in the ISP driver in the
c3-isp-params.c file.

fb2e135208f3 ("media: platform: Add C3 ISP driver")

With the recent upstreaming attempt of the Mali C55 ISP driver from Dan,
a third user of extensible parameters is going to be itroduced in the
kernel, duplicating again in the driver the procedure for validating and
handling the ISP configuration blocks

https://patchwork.linuxtv.org/project/linux-media/patch/20250624-c55-v10-15-54f3d4196990@ideasonboard.com/

To avoid duplicating again the validation routines and common types
definition, this series introduces v4l2-params.c/.h for the kAPI
and v4l2-extensible-params.h for the uAPI and re-organize the RkISP1
and Amlogic C3 drivers to use the common types and the helper validation
routines.

If the here proposed approach is accepted, I propose to rebase the Mali
C55 driver on top of this series, to use the new common types and
helpers.

I have been able to test this on RkISP1 but not on C3.

Thanks
  j

Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
Changes in v3:
- Rebased on latest media-committers/next
- Take in Dan's suggestion in block size validation
- Documentation minor spelling fixes
- Link to v2: https://lore.kernel.org/r/20250710-extensible-parameters-validation-v2-0-7ec8918ec443@ideasonboard.com

Changes in v2:
- Make v4l2_params_buffer directly usable
- Centralize ENABLE/DISABLE flags definition and validation
- Take in Dan's v4l2_params_buffer_size()
- Allow blocks to only contain the header if they're going to be
  disabled
- Documentation fixes as reported by Nicolas
- Link to v1: https://lore.kernel.org/r/20250708-extensible-parameters-validation-v1-0-9fc27c9c728c@ideasonboard.com

---
Jacopo Mondi (8):
      media: uapi: Introduce V4L2 extensible params
      media: uapi: Convert RkISP1 to V4L2 extensible params
      media: uapi: Convert Amlogic C3 to V4L2 extensible params
      media: Documentation: uapi: Add V4L2 extensible parameters
      media: v4l2-common: Introduce v4l2-params.c
      media: rkisp1: Use v4l2-params for validation
      media: amlogic-c3: Use v4l2-params for validation
      media: Documentation: kapi: Add v4l2 extensible parameters

 Documentation/driver-api/media/v4l2-core.rst       |   1 +
 Documentation/driver-api/media/v4l2-params.rst     |   5 +
 .../media/v4l/extensible-parameters.rst            |  89 ++++++
 .../userspace-api/media/v4l/meta-formats.rst       |   1 +
 MAINTAINERS                                        |  10 +
 .../media/platform/amlogic/c3/isp/c3-isp-params.c  | 263 ++++++----------
 .../media/platform/rockchip/rkisp1/rkisp1-params.c | 349 +++++++++------------
 drivers/media/v4l2-core/Makefile                   |   3 +-
 drivers/media/v4l2-core/v4l2-params.c              | 123 ++++++++
 include/media/v4l2-params.h                        | 165 ++++++++++
 include/uapi/linux/media/amlogic/c3-isp-config.h   |  48 +--
 include/uapi/linux/media/v4l2-extensible-params.h  | 144 +++++++++
 include/uapi/linux/rkisp1-config.h                 |  67 ++--
 13 files changed, 813 insertions(+), 455 deletions(-)
---
base-commit: a75b8d198c55e9eb5feb6f6e155496305caba2dc
change-id: 20250701-extensible-parameters-validation-c831f7f5cc0b

Best regards,
-- 
Jacopo Mondi <jacopo.mondi@ideasonboard.com>


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[PATCH v3 1/8] media: uapi: Introduce V4L2 extensible params

[Jacopo Mondi]

Introduce v4l2-extensible-params.h in the Linux kernel uAPI.

The header defines two types that all drivers that use the extensible
parameters format for ISP configuration shall use to build their own
format versions.

The newly introduce type v4l2_params_block represent the
header to be prepend to each ISP configuration block and the
v4l2_params_buffer type represent the base type for the configuration
parameters buffer.

The v4l2_params_buffer represents the container for the ISP
configuration data block. The generic type is defined with a 0-sized
data block that specific ISP implementation shall properly size
according to their capabilities.

[Add v4l2_params_buffer_size()]

Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 MAINTAINERS                                       |   6 +
 include/uapi/linux/media/v4l2-extensible-params.h | 144 ++++++++++++++++++++++
 2 files changed, 150 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index fe168477caa45799dfe07de2f54de6d6a1ce0615..67216d1e92d7ac81617bb3c4329e4096aa205706 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26380,6 +26380,12 @@ F:	drivers/media/i2c/vd55g1.c
 F:	drivers/media/i2c/vd56g3.c
 F:	drivers/media/i2c/vgxy61.c
 
+V4L2 EXTENSIBLE PARAMETERS FORMAT
+M:	Jacopo Mondi <jacopo.mondi@ideasonboard.com>
+L:	linux-media@vger.kernel.org
+S:	Maintained
+F:	include/uapi/linux/media/v4l2-extensible-params.h
+
 VF610 NAND DRIVER
 M:	Stefan Agner <stefan@agner.ch>
 L:	linux-mtd@lists.infradead.org
diff --git a/include/uapi/linux/media/v4l2-extensible-params.h b/include/uapi/linux/media/v4l2-extensible-params.h
new file mode 100644
index 0000000000000000000000000000000000000000..ace89299a4b37e428c0bc9a72fbc079b1dcda91a
--- /dev/null
+++ b/include/uapi/linux/media/v4l2-extensible-params.h
@@ -0,0 +1,144 @@
+/* SPDX-License-Identifier: ((GPL-2.0+ WITH Linux-syscall-note) OR MIT) */
+/*
+ * Video4Linux2 extensible configuration parameters base types
+ *
+ * Copyright (C) 2025 Ideas On Board Oy
+ * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
+ */
+
+#ifndef _UAPI_V4L2_PARAMS_H_
+#define _UAPI_V4L2_PARAMS_H_
+
+#include <linux/types.h>
+
+#define V4L2_PARAMS_FL_BLOCK_DISABLE	(1U << 0)
+#define V4L2_PARAMS_FL_BLOCK_ENABLE	(1U << 1)
+
+/*
+ * Reserve the first 8 bits for V4L2_PARAMS_FL_* flag. Platform-specific flags
+ * should be defined as:
+ * #define PLATFORM_SPECIFIC_FLAG0	((1U << V4L2_PARAMS_FL_PLATFORM_FLAGS(0))
+ * #define PLATFORM_SPECIFIC_FLAG1	((1U << V4L2_PARAMS_FL_PLATFORM_FLAGS(1))
+ */
+#define V4L2_PARAMS_FL_PLATFORM_FLAGS(n)	((n) << 8)
+
+/**
+ * struct v4l2_params_block_header - V4L2 extensible parameters block header
+ *
+ * This structure represents the common part of all the ISP configuration
+ * blocks. Each parameters block shall embed an instance of this structure type
+ * as its first member, followed by the block-specific configuration data. The
+ * driver inspects this common header to discern the block type and its size and
+ * properly handle the block content by casting it to the correct block-specific
+ * type.
+ *
+ * The @type field is one of the values enumerated by each platform-specific ISP
+ * block types which specifies how the data should be interpreted by the driver.
+ * The @size field specifies the size of the parameters block and is used by the
+ * driver for validation purposes.
+ *
+ * The @flags field is a bitmask of per-block flags V4L2_PARAMS_FL_* and
+ * platform-specific flags specified by the platform-specific header.
+ *
+ * Documentation of the platform-specific flags handling is specified by the
+ * platform-specific block header type:
+ *
+ * - Rockchip RkISP1: :c:type:`rkisp1_ext_params_block_type`
+ * - Amlogic C3: :c:type:`c3_isp_params_block_type`
+ *
+ * Userspace is responsible for correctly populating the parameters block header
+ * fields (@type, @flags and @size) and the block-specific parameters.
+ *
+ * @type: The parameters block type (platform-specific)
+ * @flags: A bitmask of block flags (platform-specific)
+ * @size: Size (in bytes) of the parameters block, including this header
+ */
+struct v4l2_params_block_header {
+	__u16 type;
+	__u16 flags;
+	__u32 size;
+} __attribute__((aligned(8)));
+
+/**
+ * v4l2_params_buffer_size - Calculate size of v4l2_params_buffer for a platform
+ *
+ * Users of the v4l2 extensible parameters will have differing sized data arrays
+ * depending on their specific parameter buffers. Drivers and userspace will
+ * need to be able to calculate the appropriate size of the struct to
+ * accommodate all ISP configuration blocks provided by the platform.
+ * This macro provides a convenient tool for the calculation.
+ *
+ * Each driver shall provide a definition of their extensible parameters
+ * implementation data buffer size. As an example:
+ *
+ * #define PLATFORM_BLOCKS_MAX_SIZE		\
+ *	sizeof(platform_block_0)	+	\
+ *	sizeof(platform_block_1)
+ *
+ * #define PLATFORM_BUFFER_SIZE			\
+ *	v4l2_params_buffer_size(PLATFORM_BLOCKS_MAX_SIZE)
+ *
+ * Drivers are then responsible for allocating buffers of the proper size
+ * by assigning PLATFORM_BUFFER_SIZE to the per-plane size of the videobuf2
+ * .queue_setup() operation and userspace shall use PLATFORM_BUFFER_SIZE
+ * when populating the ISP configuration data buffer.
+ *
+ * @max_params_size: The total size of the ISP configuration blocks
+ */
+#define v4l2_params_buffer_size(max_params_size) \
+	(offsetof(struct v4l2_params_buffer, data) + (max_params_size))
+
+/**
+ * struct v4l2_params_buffer - V4L2 extensible parameters configuration
+ *
+ * This struct contains the configuration parameters of the ISP algorithms,
+ * serialized by userspace into a data buffer. Each configuration parameter
+ * block is represented by a block-specific structure which contains a
+ * :c:type:`v4l2_params_block_header` entry as first member. Userspace populates
+ * the @data buffer with configuration parameters for the blocks that it intends
+ * to configure. As a consequence, the data buffer effective size changes
+ * according to the number of ISP blocks that userspace intends to configure and
+ * is set by userspace in the @data_size field.
+ *
+ * The parameters buffer is versioned by the @version field to allow modifying
+ * and extending its definition. Userspace shall populate the @version field to
+ * inform the driver about the version it intends to use. The driver will parse
+ * and handle the @data buffer according to the data layout specific to the
+ * indicated version and return an error if the desired version is not
+ * supported.
+ *
+ * For each ISP block that userspace wants to configure, a block-specific
+ * structure is appended to the @data buffer, one after the other without gaps
+ * in between nor overlaps. Userspace shall populate the @data_size field with
+ * the effective size, in bytes, of the @data buffer.
+ *
+ * Drivers shall take care of properly sizing of the extensible parameters
+ * buffer @data array. The v4l2_params_buffer type is defined with a
+ * flexible-array-member at the end, which resolves to a size of 0 bytes when
+ * inspected with sizeof(struct v4l2_params_buffer). This of course is not
+ * suitable for neither buffer allocation in the kernel driver nor for proper
+ * handling in userspace of the @data buffer it has to populate.
+ *
+ * Drivers using this type in their userspace API definition are responsible
+ * for providing the exact definition of the @data buffer size using the
+ * v4l2_params_buffer_size() macro. The size shall be used
+ * by the driver for buffers allocation and by userspace for populating the
+ * @data buffer before queueing it to the driver
+ *
+ * Drivers that were already using extensible-parameters before the introduction
+ * of this file define their own type-convertible implementation of this
+ * type, see:
+ * - Rockchip RkISP1: :c:type:`rkisp1_ext_params_cfg`
+ * - Amlogic C3: :c:type:`c3_isp_params_cfg`
+ *
+ * @version: The parameters buffer version (platform-specific)
+ * @data_size: The configuration data effective size, excluding this header
+ * @data: The configuration data
+ */
+struct v4l2_params_buffer {
+	__u32 version;
+	__u32 data_size;
+	__u8 data[];
+};
+
+#endif /* _UAPI_V4L2_PARAMS_H_ */

-- 
2.50.1


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[PATCH v3 2/8] media: uapi: Convert RkISP1 to V4L2 extensible params

[Jacopo Mondi]

With the introduction of common types for extensible parameters
format, convert the rkisp1-config.h header to use the new types.

Factor-out the documentation that is now part of the common header
and only keep the driver-specific on in place.

The conversion to use common types doesn't impact userspace as the
new types are either identical to the ones already existing in the
RkISP1 uAPI or are 1-to-1 type convertible.

Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 include/uapi/linux/rkisp1-config.h | 67 +++++++++++++-------------------------
 1 file changed, 23 insertions(+), 44 deletions(-)

diff --git a/include/uapi/linux/rkisp1-config.h b/include/uapi/linux/rkisp1-config.h
index 3b060ea6eed71b87d79abc8401eae4e9c9f5323a..fc040c7fb13cf18eaf8d9067e7be38bff120e6f6 100644
--- a/include/uapi/linux/rkisp1-config.h
+++ b/include/uapi/linux/rkisp1-config.h
@@ -7,8 +7,13 @@
 #ifndef _UAPI_RKISP1_CONFIG_H
 #define _UAPI_RKISP1_CONFIG_H
 
+#ifdef __KERNEL__
+#include <linux/build_bug.h>
+#endif /* __KERNEL__ */
 #include <linux/types.h>
 
+#include <linux/media/v4l2-extensible-params.h>
+
 /* Defect Pixel Cluster Detection */
 #define RKISP1_CIF_ISP_MODULE_DPCC		(1U << 0)
 /* Black Level Subtraction */
@@ -1158,26 +1163,21 @@ enum rkisp1_ext_params_block_type {
 	RKISP1_EXT_PARAMS_BLOCK_TYPE_WDR,
 };
 
-#define RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE	(1U << 0)
-#define RKISP1_EXT_PARAMS_FL_BLOCK_ENABLE	(1U << 1)
+#define RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE	V4L2_PARAMS_FL_BLOCK_DISABLE
+#define RKISP1_EXT_PARAMS_FL_BLOCK_ENABLE	V4L2_PARAMS_FL_BLOCK_ENABLE
 
 /* A bitmask of parameters blocks supported on the current hardware. */
 #define RKISP1_CID_SUPPORTED_PARAMS_BLOCKS	(V4L2_CID_USER_RKISP1_BASE + 0x01)
 
 /**
- * struct rkisp1_ext_params_block_header - RkISP1 extensible parameters block
- *					   header
+ * rkisp1_ext_params_block_header - RkISP1 extensible parameters block header
  *
  * This structure represents the common part of all the ISP configuration
- * blocks. Each parameters block shall embed an instance of this structure type
- * as its first member, followed by the block-specific configuration data. The
- * driver inspects this common header to discern the block type and its size and
- * properly handle the block content by casting it to the correct block-specific
- * type.
+ * blocks and is identical to :c:type:`v4l2_params_block_header`.
  *
- * The @type field is one of the values enumerated by
+ * The type field is one of the values enumerated by
  * :c:type:`rkisp1_ext_params_block_type` and specifies how the data should be
- * interpreted by the driver. The @size field specifies the size of the
+ * interpreted by the driver. The size field specifies the size of the
  * parameters block and is used by the driver for validation purposes.
  *
  * The @flags field is a bitmask of per-block flags RKISP1_EXT_PARAMS_FL_*.
@@ -1193,14 +1193,14 @@ enum rkisp1_ext_params_block_type {
  * If a new configuration of an ISP block has to be applied userspace shall
  * fully populate the ISP block configuration and omit setting the
  * RKISP1_EXT_PARAMS_FL_BLOCK_ENABLE and RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE bits
- * in the @flags field.
+ * in the flags field.
  *
  * Setting both the RKISP1_EXT_PARAMS_FL_BLOCK_ENABLE and
- * RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE bits in the @flags field is not allowed
+ * RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE bits in the flags field is not allowed
  * and not accepted by the driver.
  *
  * Userspace is responsible for correctly populating the parameters block header
- * fields (@type, @flags and @size) and the block-specific parameters.
+ * fields (type, flags and size) and the block-specific parameters.
  *
  * For example:
  *
@@ -1220,17 +1220,8 @@ enum rkisp1_ext_params_block_type {
  *		bls->config.fixed_val.gb = blackLevelGreenB_;
  *		bls->config.fixed_val.b = blackLevelBlue_;
  *	}
- *
- * @type: The parameters block type, see
- *	  :c:type:`rkisp1_ext_params_block_type`
- * @flags: A bitmask of block flags
- * @size: Size (in bytes) of the parameters block, including this header
  */
-struct rkisp1_ext_params_block_header {
-	__u16 type;
-	__u16 flags;
-	__u32 size;
-};
+#define rkisp1_ext_params_block_header v4l2_params_block_header
 
 /**
  * struct rkisp1_ext_params_bls_config - RkISP1 extensible params BLS config
@@ -1594,21 +1585,7 @@ enum rksip1_ext_param_buffer_version {
 /**
  * struct rkisp1_ext_params_cfg - RkISP1 extensible parameters configuration
  *
- * This struct contains the configuration parameters of the RkISP1 ISP
- * algorithms, serialized by userspace into a data buffer. Each configuration
- * parameter block is represented by a block-specific structure which contains a
- * :c:type:`rkisp1_ext_params_block_header` entry as first member. Userspace
- * populates the @data buffer with configuration parameters for the blocks that
- * it intends to configure. As a consequence, the data buffer effective size
- * changes according to the number of ISP blocks that userspace intends to
- * configure and is set by userspace in the @data_size field.
- *
- * The parameters buffer is versioned by the @version field to allow modifying
- * and extending its definition. Userspace shall populate the @version field to
- * inform the driver about the version it intends to use. The driver will parse
- * and handle the @data buffer according to the data layout specific to the
- * indicated version and return an error if the desired version is not
- * supported.
+ * This is the driver-specific implementation of :c:type:`v4l2_params_buffer`.
  *
  * Currently the single RKISP1_EXT_PARAM_BUFFER_V1 version is supported.
  * When a new format version will be added, a mechanism for userspace to query
@@ -1624,11 +1601,6 @@ enum rksip1_ext_param_buffer_version {
  * the maximum value represents the blocks supported by the kernel driver,
  * independently of the device instance.
  *
- * For each ISP block that userspace wants to configure, a block-specific
- * structure is appended to the @data buffer, one after the other without gaps
- * in between nor overlaps. Userspace shall populate the @data_size field with
- * the effective size, in bytes, of the @data buffer.
- *
  * The expected memory layout of the parameters buffer is::
  *
  *	+-------------------- struct rkisp1_ext_params_cfg -------------------+
@@ -1678,4 +1650,11 @@ struct rkisp1_ext_params_cfg {
 	__u8 data[RKISP1_EXT_PARAMS_MAX_SIZE];
 };
 
+#ifdef __KERNEL__
+/* Make sure the header is type-convertible to the generic v4l2 params one */
+static_assert((sizeof(struct rkisp1_ext_params_cfg) -
+	      RKISP1_EXT_PARAMS_MAX_SIZE) ==
+	      sizeof(struct v4l2_params_buffer));
+#endif /* __KERNEL__ */
+
 #endif /* _UAPI_RKISP1_CONFIG_H */

-- 
2.50.1


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[PATCH v3 3/8] media: uapi: Convert Amlogic C3 to V4L2 extensible params

[Jacopo Mondi]

With the introduction of common types for extensible parameters
format, convert the c3-isp-config.h header to use the new types.

Factor-out the documentation that is now part of the common header
and only keep the driver-specific on in place.

The conversion to use common types doesn't impact userspace as the
new types are either identical to the ones already existing in the
C3 ISP uAPI or are 1-to-1 type convertible.

Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Keke Li <keke.li@amlogic.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 include/uapi/linux/media/amlogic/c3-isp-config.h | 48 ++++++++----------------
 1 file changed, 15 insertions(+), 33 deletions(-)

diff --git a/include/uapi/linux/media/amlogic/c3-isp-config.h b/include/uapi/linux/media/amlogic/c3-isp-config.h
index ed085ea62a574932c7ad8d59d34b2c5c74a597d8..15d3ac289ece610132e1d4b43ecd56b7ef527ef6 100644
--- a/include/uapi/linux/media/amlogic/c3-isp-config.h
+++ b/include/uapi/linux/media/amlogic/c3-isp-config.h
@@ -6,8 +6,13 @@
 #ifndef _UAPI_C3_ISP_CONFIG_H_
 #define _UAPI_C3_ISP_CONFIG_H_
 
+#ifdef __KERNEL__
+#include <linux/build_bug.h>
+#endif /* __KERNEL__ */
 #include <linux/types.h>
 
+#include <linux/media/v4l2-extensible-params.h>
+
 /*
  * Frames are split into zones of almost equal width and height - a zone is a
  * rectangular tile of a frame. The metering blocks within the ISP collect
@@ -183,11 +188,6 @@ enum c3_isp_params_block_type {
  * struct c3_isp_params_block_header - C3 ISP parameter block header
  *
  * This structure represents the common part of all the ISP configuration
- * blocks. Each parameters block shall embed an instance of this structure type
- * as its first member, followed by the block-specific configuration data. The
- * driver inspects this common header to discern the block type and its size and
- * properly handle the block content by casting it to the correct block-specific
- * type.
  *
  * The @type field is one of the values enumerated by
  * :c:type:`c3_isp_params_block_type` and specifies how the data should be
@@ -223,15 +223,8 @@ enum c3_isp_params_block_type {
  *			gamma->pst_gamma_lut[i] = i;
  *	}
  *
- * @type: The parameters block type from :c:type:`c3_isp_params_block_type`
- * @flags: A bitmask of block flags
- * @size: Size (in bytes) of the parameters block, including this header
  */
-struct c3_isp_params_block_header {
-	__u16 type;
-	__u16 flags;
-	__u32 size;
-};
+#define c3_isp_params_block_header v4l2_params_block_header
 
 /**
  * struct c3_isp_params_awb_gains - Gains for auto-white balance
@@ -498,26 +491,9 @@ struct c3_isp_params_blc {
 /**
  * struct c3_isp_params_cfg - C3 ISP configuration parameters
  *
- * This struct contains the configuration parameters of the C3 ISP
- * algorithms, serialized by userspace into an opaque data buffer. Each
- * configuration parameter block is represented by a block-specific structure
- * which contains a :c:type:`c3_isp_param_block_header` entry as first
- * member. Userspace populates the @data buffer with configuration parameters
- * for the blocks that it intends to configure. As a consequence, the data
- * buffer effective size changes according to the number of ISP blocks that
- * userspace intends to configure.
- *
- * The parameters buffer is versioned by the @version field to allow modifying
- * and extending its definition. Userspace should populate the @version field to
- * inform the driver about the version it intends to use. The driver will parse
- * and handle the @data buffer according to the data layout specific to the
- * indicated revision and return an error if the desired revision is not
- * supported.
- *
- * For each ISP block that userspace wants to configure, a block-specific
- * structure is appended to the @data buffer, one after the other without gaps
- * in between nor overlaps. Userspace shall populate the @total_size field with
- * the effective size, in bytes, of the @data buffer.
+ * This is the driver-specific implementation of :c:type:`v4l2_params_buffer`.
+ *
+ * Currently only C3_ISP_PARAM_BUFFER_V0 is supported.
  *
  * The expected memory layout of the parameters buffer is::
  *
@@ -561,4 +537,10 @@ struct c3_isp_params_cfg {
 	__u8 data[C3_ISP_PARAMS_MAX_SIZE];
 };
 
+#ifdef __KERNEL__
+/* Make sure the header is type-convertible to the generic v4l2 params one */
+static_assert((sizeof(struct c3_isp_params_cfg) - C3_ISP_PARAMS_MAX_SIZE) ==
+	      sizeof(struct v4l2_params_buffer));
+#endif /* __KERNEL__ */
+
 #endif

-- 
2.50.1


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[PATCH v3 4/8] media: Documentation: uapi: Add V4L2 extensible parameters

[Jacopo Mondi]

Add documentation for extensible parameters format to the V4L2
userspace API documentation.

Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 .../media/v4l/extensible-parameters.rst            | 89 ++++++++++++++++++++++
 .../userspace-api/media/v4l/meta-formats.rst       |  1 +
 MAINTAINERS                                        |  1 +
 3 files changed, 91 insertions(+)

diff --git a/Documentation/userspace-api/media/v4l/extensible-parameters.rst b/Documentation/userspace-api/media/v4l/extensible-parameters.rst
new file mode 100644
index 0000000000000000000000000000000000000000..c4caa5c1df991d4dd91f986571db55135d15204a
--- /dev/null
+++ b/Documentation/userspace-api/media/v4l/extensible-parameters.rst
@@ -0,0 +1,89 @@
+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+
+.. _extensible-parameters:
+
+**********************************
+ V4L2 extensible parameters format
+**********************************
+
+ISP configuration
+=================
+
+ISP configuration parameters are computed by userspace and programmed into a
+*parameters buffer* which is queued to the ISP driver on a per-frame basis. The
+layout of the *parameters buffer* generally reflects the ISP peripheral
+registers layout and is, for this reason, platform specific.
+
+The ISP configuration parameters are passed to the ISP driver through a metadata
+output video node, using the :c:type:`v4l2_meta_format` interface. Each ISP
+driver defines a metadata format that implements the configuration parameters
+layout.
+
+Metadata output formats that describe ISP configuration parameters are most of
+the time realized by implementing C structures that reflect the registers layout
+and gets populated by userspace before queueing the buffer to the ISP. Each
+C structure usually corresponds to one ISP *processing block*, with each block
+implementing one of the ISP supported features.
+
+The uAPI/ABI problem
+--------------------
+
+By upstreaming data types that describe the configuration parameters layout,
+driver developers make them part of the Linux kernel ABI. As it sometimes
+happens for most peripherals in Linux, ISP drivers development is often an
+iterative process, where sometimes not all the hardware features are supported
+in the first version that lands in the kernel, and some parts of the interface
+have to later be modified for bug-fixes or improvements.
+
+If any later bug-fix/improvement requires changes to the metadata output format,
+this is considered an ABI-breakage that is strictly forbidden by the Linux
+kernel policies. For this reason, each new iteration of an ISP driver support
+would require defining a new metadata output format, implying that drivers have
+to be made ready to handle several different configuration formats.
+
+A new set of metadata output formats has then to be defined, with the design
+goals of being:
+
+- Extensible: new features can be added later on without breaking the existing
+  interface
+- Versioned: different versions of the format can be defined without
+  breaking the existing interface
+
+The extensible parameters format
+================================
+
+Extensible configuration formats are realized by a defining a single C structure
+that contains a few control parameters and a binary buffer where userspace
+programs a variable number of *ISP configuration blocks* data.
+
+The generic :c:type:`v4l2_params_buffer` defines a base type that each driver
+can use by properly sizing the data buffer array.
+
+Each *ISP configuration block* is identified by an header and contains the
+parameters for that specific block.
+
+The generic :c:type:`v4l2_params_block_header` defines a base type that each
+driver can re-use as it is or extend appropriately.
+
+Userspace applications program in the control buffer only the parameters of the
+ISP whose configuration has changed for the next frame. The ISP driver parses
+the configuration parameters and apply them to the hardware register.
+
+Any further development that happens after the ISP driver has been merged in
+Linux and which requires supporting new ISP features can be implemented by
+adding new blocks definition without invalidating the existing ones. Similarly,
+any change to the existing ISP configuration blocks can be handled by versioning
+them, again without invalidating the existing ones.
+
+Implementations
+---------------
+
+ISP drivers that define an extensible parameters metadata output format:
+
+- :ref:`RkISP1 <v4l2-meta-fmt-rk-isp1-ext-params>`
+- :ref:`Amlogic C3 ISP <v4l2-meta-fmt-c3isp-params>`
+
+V4L2 extensible parameters uAPI data types
+==========================================
+
+.. kernel-doc:: include/uapi/linux/media/v4l2-extensible-params.h
diff --git a/Documentation/userspace-api/media/v4l/meta-formats.rst b/Documentation/userspace-api/media/v4l/meta-formats.rst
index 0de80328c36bf148051a19abe9e5241234ddfe5c..b900ed6af7bd9ad49baf7b5a9eef9423f8abfbcb 100644
--- a/Documentation/userspace-api/media/v4l/meta-formats.rst
+++ b/Documentation/userspace-api/media/v4l/meta-formats.rst
@@ -12,6 +12,7 @@ These formats are used for the :ref:`metadata` interface only.
 .. toctree::
     :maxdepth: 1
 
+    extensible-parameters
     metafmt-c3-isp
     metafmt-d4xx
     metafmt-generic
diff --git a/MAINTAINERS b/MAINTAINERS
index 67216d1e92d7ac81617bb3c4329e4096aa205706..91df04e5d9022ccf2aea4445247369a8b86a4264 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26384,6 +26384,7 @@ V4L2 EXTENSIBLE PARAMETERS FORMAT
 M:	Jacopo Mondi <jacopo.mondi@ideasonboard.com>
 L:	linux-media@vger.kernel.org
 S:	Maintained
+F:	Documentation/userspace-api/media/v4l/extensible-parameters.rst
 F:	include/uapi/linux/media/v4l2-extensible-params.h
 
 VF610 NAND DRIVER

-- 
2.50.1


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[PATCH v3 5/8] media: v4l2-common: Introduce v4l2-params.c

[Jacopo Mondi]

Add to the v4l2 framework an helper function to support drivers
when validating a buffer of extensible parameters.

Introduce new types in include/media/v4l2-params.h that drivers shall
use in order to comply with the v4l2-params validation procedure, and
add a helper functions to v4l2-params.c to perform block and buffer
validation.

Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 MAINTAINERS                           |   2 +
 drivers/media/v4l2-core/Makefile      |   3 +-
 drivers/media/v4l2-core/v4l2-params.c | 123 +++++++++++++++++++++++++
 include/media/v4l2-params.h           | 165 ++++++++++++++++++++++++++++++++++
 4 files changed, 292 insertions(+), 1 deletion(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 91df04e5d9022ccf2aea4445247369a8b86a4264..008f984c0769691f6ddec8d8f0f461fde056ddb3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26385,6 +26385,8 @@ M:	Jacopo Mondi <jacopo.mondi@ideasonboard.com>
 L:	linux-media@vger.kernel.org
 S:	Maintained
 F:	Documentation/userspace-api/media/v4l/extensible-parameters.rst
+F:	drivers/media/v4l2-core/v4l2-params.c
+F:	include/media/v4l2-params.h
 F:	include/uapi/linux/media/v4l2-extensible-params.h
 
 VF610 NAND DRIVER
diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
index 2177b9d63a8ffc1127c5a70118249a2ff63cd759..323330dd359f95c1ae3d0c35bd6fcb8291a33a07 100644
--- a/drivers/media/v4l2-core/Makefile
+++ b/drivers/media/v4l2-core/Makefile
@@ -11,7 +11,8 @@ tuner-objs	:=	tuner-core.o
 videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \
 			v4l2-event.o v4l2-subdev.o v4l2-common.o \
 			v4l2-ctrls-core.o v4l2-ctrls-api.o \
-			v4l2-ctrls-request.o v4l2-ctrls-defs.o
+			v4l2-ctrls-request.o v4l2-ctrls-defs.o \
+			v4l2-params.o
 
 # Please keep it alphabetically sorted by Kconfig name
 # (e. g. LC_ALL=C sort Makefile)
diff --git a/drivers/media/v4l2-core/v4l2-params.c b/drivers/media/v4l2-core/v4l2-params.c
new file mode 100644
index 0000000000000000000000000000000000000000..8eeb12414c0981c13725a59d1668c5798b9fcf50
--- /dev/null
+++ b/drivers/media/v4l2-core/v4l2-params.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Video4Linux2 extensible parameters helpers
+ *
+ * Copyright (C) 2025 Ideas On Board Oy
+ * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
+ */
+
+#include <media/v4l2-params.h>
+
+int v4l2_params_buffer_validate(struct device *dev, struct vb2_buffer *vb,
+				size_t max_size,
+				v4l2_params_validate_buffer buffer_validate)
+{
+	size_t header_size = offsetof(struct v4l2_params_buffer, data);
+	struct v4l2_params_buffer *buffer = vb2_plane_vaddr(vb, 0);
+	size_t payload_size = vb2_get_plane_payload(vb, 0);
+	size_t buffer_size;
+	int ret;
+
+	/* Payload size can't be greater than the destination buffer size */
+	if (payload_size > max_size) {
+		dev_dbg(dev, "Payload size is too large: %zu\n", payload_size);
+		return -EINVAL;
+	}
+
+	/* Payload size can't be smaller than the header size */
+	if (payload_size < header_size) {
+		dev_dbg(dev, "Payload size is too small: %zu\n", payload_size);
+		return -EINVAL;
+	}
+
+	/* Validate the size reported in the parameter buffer header */
+	buffer_size = header_size + buffer->data_size;
+	if (buffer_size != payload_size) {
+		dev_dbg(dev, "Data size %zu and payload size %zu are different\n",
+			buffer_size, payload_size);
+		return -EINVAL;
+	}
+
+	/* Driver-specific buffer validation. */
+	if (buffer_validate) {
+		ret = buffer_validate(dev, buffer);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_params_buffer_validate);
+
+int v4l2_params_blocks_validate(struct device *dev,
+				const struct v4l2_params_buffer *buffer,
+				const struct v4l2_params_handler *handlers,
+				size_t num_handlers,
+				v4l2_params_validate_block block_validate)
+{
+	size_t block_offset = 0;
+	size_t buffer_size;
+	int ret;
+
+	/* Walk the list of parameter blocks and validate them. */
+	buffer_size = buffer->data_size;
+	while (buffer_size >= sizeof(struct v4l2_params_block_header)) {
+		const struct v4l2_params_handler *handler;
+		const struct v4l2_params_block_header *block;
+
+		/* Validate block sizes and types against the handlers. */
+		block = (const struct v4l2_params_block_header *)
+			(buffer->data + block_offset);
+
+		if (block->type >= num_handlers) {
+			dev_dbg(dev, "Invalid parameters block type\n");
+			return -EINVAL;
+		}
+
+		if (block->size > buffer_size) {
+			dev_dbg(dev, "Premature end of parameters data\n");
+			return -EINVAL;
+		}
+
+		/* It's invalid to specify both ENABLE and DISABLE. */
+		if ((block->flags & (V4L2_PARAMS_FL_BLOCK_ENABLE |
+				     V4L2_PARAMS_FL_BLOCK_DISABLE)) ==
+		     (V4L2_PARAMS_FL_BLOCK_ENABLE |
+		     V4L2_PARAMS_FL_BLOCK_DISABLE)) {
+			dev_dbg(dev, "Invalid parameters block flags\n");
+			return -EINVAL;
+		}
+
+		/*
+		 * Match the block reported size against the handler's expected
+		 * one, but allow the block to only contain the header in
+		 * case it is going to be disabled.
+		 */
+		handler = &handlers[block->type];
+		if (block->size != handler->size) {
+			if (!(block->flags & V4L2_PARAMS_FL_BLOCK_DISABLE) ||
+			      block->size != sizeof(*block)) {
+				dev_dbg(dev, "Invalid parameters block size\n");
+				return -EINVAL;
+			}
+		}
+
+		/* Driver-specific per-block validation. */
+		if (block_validate) {
+			ret = block_validate(dev, block);
+			if (ret)
+				return ret;
+		}
+
+		block_offset += block->size;
+		buffer_size -= block->size;
+	}
+
+	if (buffer_size) {
+		dev_dbg(dev, "Unexpected data after the parameters buffer end\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_params_blocks_validate);
diff --git a/include/media/v4l2-params.h b/include/media/v4l2-params.h
new file mode 100644
index 0000000000000000000000000000000000000000..a8a4cc721bc4a51d8a6f9c7c009b34dfa3579229
--- /dev/null
+++ b/include/media/v4l2-params.h
@@ -0,0 +1,165 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Video4Linux2 extensible parameters helpers
+ *
+ * Copyright (C) 2025 Ideas On Board Oy
+ * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
+ */
+
+#ifndef V4L2_PARAMS_H_
+#define V4L2_PARAMS_H_
+
+#include <linux/media/v4l2-extensible-params.h>
+
+#include <linux/device.h>
+
+#include <media/videobuf2-core.h>
+
+/**
+ * typedef v4l2_params_block_handler - V4L2 extensible format block handler
+ * @arg: pointer the driver-specific argument
+ * @block: the ISP configuration block to handle
+ *
+ * Defines the function signature of the functions that handle an ISP block
+ * configuration.
+ */
+typedef void (*v4l2_params_block_handler)(void *arg,
+					  const struct v4l2_params_block_header *block);
+
+/**
+ * struct v4l2_params_handler - V4L2 extensible format handler
+ * @size: the block expected size
+ * @handler: the block handler function
+ * @group: the device-specific group id the block belongs to (optional)
+ * @features: the device-specific features flags (optional)
+ *
+ * The v4l2_params_handler defines the type that driver making use of the
+ * V4L2 extensible parameters shall use to define their own ISP block
+ * handlers.
+ *
+ * Drivers shall prepare a list of handlers, one for each supported ISP block
+ * and correctly populate the structure's field with the expected block @size
+ * (used for validation), a pointer to each block @handler function and an
+ * optional @group and @feature flags, the driver can use to differentiate which
+ * ISP blocks are present on the ISP implementation.
+ *
+ * The @group field is intended to be used as a bitmask of driver-specific
+ * flags to allow the driver to setup certain blocks at different times. As an
+ * example an ISP driver can divide its block handlers in "pre-configure" blocks
+ * and "run-time" blocks and use the @group bitmask to identify the ISP blocks
+ * that have to be pre-configured from the ones that only have to be handled at
+ * run-time. The usage and definition of the @group field is totally
+ * driver-specific.
+ *
+ * The @features flag can instead be used to differentiate between blocks
+ * implemented in different revisions of the ISP design. In example some ISP
+ * blocks might be present on more recent revision than others. Populating the
+ * @features bitmask with the ISP/SoC machine identifier allows the driver to
+ * correctly ignore the blocks not supported on the ISP revision it is running
+ * on. As per the @group bitmask, the usage and definition of the @features
+ * field is totally driver-specific.
+ */
+struct v4l2_params_handler {
+	size_t size;
+	v4l2_params_block_handler handler;
+	unsigned int group;
+	unsigned int features;
+};
+
+/**
+ * typedef v4l2_params_validate_buffer - V4L2 extensible parameters buffer
+ *					 validation callback
+ * @dev: the driver's device pointer (as passed by the driver to
+ *	 v4l2_params_buffer_validate())
+ * @buffer: the extensible parameters buffer
+ *
+ * Defines the function prototype for the driver's callback to perform
+ * driver-specific validation on the extensible parameters buffer
+ */
+typedef int (*v4l2_params_validate_buffer)(struct device *dev,
+					   const struct v4l2_params_buffer *buffer);
+
+/**
+ * v4l2_params_buffer_validate - Validate a V4L2 extensible parameters buffer
+ * @dev: the driver's device pointer
+ * @vb: the videobuf2 buffer
+ * @max_size: the maximum allowed buffer size
+ * @buffer_validate: callback to the driver-specific buffer validation
+ *
+ * Helper function that performs validation of an extensible parameters buffer.
+ *
+ * The helper is meant to be used by drivers to perform validation of the
+ * extensible parameters buffer size correctness.
+ *
+ * The @vb buffer as received from the vb2 .buf_prepare() operation is checked
+ * against @max_size and its validated to be large enough to accommodate at
+ * least one ISP configuration block. The effective buffer size is compared
+ * with the reported data size to make sure they match.
+ *
+ * If provided, the @buffer_validate callback function is invoked to allow
+ * drivers to perform driver-specific validation (such as checking that the
+ * buffer version is supported).
+ *
+ * Drivers should use this function to validate the buffer size correctness
+ * before performing a copy of the user-provided videobuf2 buffer content into a
+ * kernel-only memory buffer to prevent userspace from modifying the buffer
+ * content after it has been submitted to the driver.
+ *.
+ * Examples of users of this function can be found in
+ * rkisp1_params_prepare_ext_params() and in c3_isp_params_vb2_buf_prepare().
+ */
+int v4l2_params_buffer_validate(struct device *dev, struct vb2_buffer *vb,
+				size_t max_size,
+				v4l2_params_validate_buffer buffer_validate);
+
+/**
+ * typedef v4l2_params_validate_block - V4L2 extensible parameters block
+ *					validation callback
+ * @dev: the driver's device pointer (as passed by the driver to
+ *	 v4l2_params_validate())
+ * @block: the ISP configuration block to validate
+ *
+ * Defines the function prototype for the driver's callback to perform
+ * driver-specific validation on each ISP block.
+ */
+typedef int (*v4l2_params_validate_block)(struct device *dev,
+					  const struct v4l2_params_block_header *block);
+
+/**
+ * v4l2_params_blocks_validate - Validate V4L2 extensible parameters ISP
+ *				 configuration blocks
+ * @dev: the driver's device pointer
+ * @buffer: the extensible parameters configuration buffer
+ * @handlers: the list of block handlers
+ * @num_handlers: the number of block handlers
+ * @block_validate: callback to the driver-specific per-block validation
+ *		    function
+ *
+ * Helper function that performs validation of the ISP configuration blocks in
+ * an extensible parameters buffer.
+ *
+ * The helper is meant to be used by drivers to perform validation of the
+ * ISP configuration data blocks. For each block in the extensible parameters
+ * buffer, its size and correctness are validated against its associated handler
+ * in the @handlers list. Additionally, if provided, the @block_validate
+ * callback is invoked on each block to allow drivers to perform driver-specific
+ * validation.
+ *
+ * Drivers should use this function to validate the ISP configuration blocks
+ * after having validated the correctness of the vb2 buffer sizes by using the
+ * v4l2_params_buffer_validate() helper first. Once the buffer size has been
+ * validated, drivers should perform a copy of the user-provided buffer into a
+ * kernel-only memory buffer to prevent userspace from modifying the buffer
+ * content after it has been submitted to the driver, and then call this
+ * function to perform per-block validation.
+ *
+ * Examples of users of this function can be found in
+ * rkisp1_params_prepare_ext_params() and in c3_isp_params_vb2_buf_prepare().
+ */
+int v4l2_params_blocks_validate(struct device *dev,
+				const struct v4l2_params_buffer *buffer,
+				const struct v4l2_params_handler *handlers,
+				size_t num_handlers,
+				v4l2_params_validate_block block_validate);
+
+#endif /* V4L2_PARAMS_H_ */

-- 
2.50.1


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[PATCH v3 6/8] media: rkisp1: Use v4l2-params for validation

[Jacopo Mondi]

Convert rkisp1-params.c to use the new types for block handlers
defined in v4l2-params.h and use the new helpers from v4l2-params.c
to remove bolierplate code from the driver.

Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 .../media/platform/rockchip/rkisp1/rkisp1-params.c | 349 +++++++++------------
 1 file changed, 141 insertions(+), 208 deletions(-)

diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
index f1585f8fa0f478304f74317fd9dd09199c94ec82..d7bfb1b50ed7e8dec5a20aec6cd775b721091abf 100644
--- a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
+++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
@@ -12,6 +12,7 @@
 #include <media/v4l2-common.h>
 #include <media/v4l2-event.h>
 #include <media/v4l2-ioctl.h>
+#include <media/v4l2-params.h>
 #include <media/videobuf2-core.h>
 #include <media/videobuf2-vmalloc.h>	/* for ISP params */
 
@@ -40,30 +41,6 @@
 #define RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS	BIT(0)
 #define RKISP1_EXT_PARAMS_BLOCK_GROUP_LSC	BIT(1)
 
-union rkisp1_ext_params_config {
-	struct rkisp1_ext_params_block_header header;
-	struct rkisp1_ext_params_bls_config bls;
-	struct rkisp1_ext_params_dpcc_config dpcc;
-	struct rkisp1_ext_params_sdg_config sdg;
-	struct rkisp1_ext_params_lsc_config lsc;
-	struct rkisp1_ext_params_awb_gain_config awbg;
-	struct rkisp1_ext_params_flt_config flt;
-	struct rkisp1_ext_params_bdm_config bdm;
-	struct rkisp1_ext_params_ctk_config ctk;
-	struct rkisp1_ext_params_goc_config goc;
-	struct rkisp1_ext_params_dpf_config dpf;
-	struct rkisp1_ext_params_dpf_strength_config dpfs;
-	struct rkisp1_ext_params_cproc_config cproc;
-	struct rkisp1_ext_params_ie_config ie;
-	struct rkisp1_ext_params_awb_meas_config awbm;
-	struct rkisp1_ext_params_hst_config hst;
-	struct rkisp1_ext_params_aec_config aec;
-	struct rkisp1_ext_params_afc_config afc;
-	struct rkisp1_ext_params_compand_bls_config compand_bls;
-	struct rkisp1_ext_params_compand_curve_config compand_curve;
-	struct rkisp1_ext_params_wdr_config wdr;
-};
-
 enum rkisp1_params_formats {
 	RKISP1_PARAMS_FIXED,
 	RKISP1_PARAMS_EXTENSIBLE,
@@ -1689,11 +1666,12 @@ static void rkisp1_isp_isr_meas_config(struct rkisp1_params *params,
  * Extensible parameters format handling
  */
 
-static void
-rkisp1_ext_params_bls(struct rkisp1_params *params,
-		      const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_bls(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_bls_config *bls = &block->bls;
+	const struct rkisp1_ext_params_bls_config *bls =
+		(const struct rkisp1_ext_params_bls_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (bls->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_BLS_CTRL,
@@ -1709,11 +1687,12 @@ rkisp1_ext_params_bls(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_BLS_ENA);
 }
 
-static void
-rkisp1_ext_params_dpcc(struct rkisp1_params *params,
-		       const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_dpcc(void *dev,
+				   const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_dpcc_config *dpcc = &block->dpcc;
+	const struct rkisp1_ext_params_dpcc_config *dpcc =
+		(const struct rkisp1_ext_params_dpcc_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (dpcc->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_DPCC_MODE,
@@ -1729,11 +1708,12 @@ rkisp1_ext_params_dpcc(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_DPCC_MODE_DPCC_ENABLE);
 }
 
-static void
-rkisp1_ext_params_sdg(struct rkisp1_params *params,
-		      const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_sdg(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_sdg_config *sdg = &block->sdg;
+	const struct rkisp1_ext_params_sdg_config *sdg =
+		(const struct rkisp1_ext_params_sdg_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (sdg->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_CTRL,
@@ -1749,11 +1729,12 @@ rkisp1_ext_params_sdg(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_CTRL_ISP_GAMMA_IN_ENA);
 }
 
-static void
-rkisp1_ext_params_lsc(struct rkisp1_params *params,
-		      const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_lsc(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_lsc_config *lsc = &block->lsc;
+	const struct rkisp1_ext_params_lsc_config *lsc =
+		(const struct rkisp1_ext_params_lsc_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (lsc->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_LSC_CTRL,
@@ -1769,11 +1750,12 @@ rkisp1_ext_params_lsc(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_LSC_CTRL_ENA);
 }
 
-static void
-rkisp1_ext_params_awbg(struct rkisp1_params *params,
-		       const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_awbg(void *dev,
+				   const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_awb_gain_config *awbg = &block->awbg;
+	const struct rkisp1_ext_params_awb_gain_config *awbg =
+		(const struct rkisp1_ext_params_awb_gain_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (awbg->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_CTRL,
@@ -1789,11 +1771,12 @@ rkisp1_ext_params_awbg(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_CTRL_ISP_AWB_ENA);
 }
 
-static void
-rkisp1_ext_params_flt(struct rkisp1_params *params,
-		      const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_flt(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_flt_config *flt = &block->flt;
+	const struct rkisp1_ext_params_flt_config *flt =
+		(const struct rkisp1_ext_params_flt_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (flt->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_FILT_MODE,
@@ -1809,11 +1792,12 @@ rkisp1_ext_params_flt(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_FLT_ENA);
 }
 
-static void
-rkisp1_ext_params_bdm(struct rkisp1_params *params,
-		      const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_bdm(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_bdm_config *bdm = &block->bdm;
+	const struct rkisp1_ext_params_bdm_config *bdm =
+		(const struct rkisp1_ext_params_bdm_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (bdm->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_DEMOSAIC,
@@ -1829,11 +1813,12 @@ rkisp1_ext_params_bdm(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_DEMOSAIC_BYPASS);
 }
 
-static void
-rkisp1_ext_params_ctk(struct rkisp1_params *params,
-		      const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_ctk(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_ctk_config *ctk = &block->ctk;
+	const struct rkisp1_ext_params_ctk_config *ctk =
+		(const struct rkisp1_ext_params_ctk_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (ctk->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_ctk_enable(params, false);
@@ -1847,11 +1832,12 @@ rkisp1_ext_params_ctk(struct rkisp1_params *params,
 		rkisp1_ctk_enable(params, true);
 }
 
-static void
-rkisp1_ext_params_goc(struct rkisp1_params *params,
-		      const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_goc(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_goc_config *goc = &block->goc;
+	const struct rkisp1_ext_params_goc_config *goc =
+		(const struct rkisp1_ext_params_goc_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (goc->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_CTRL,
@@ -1869,11 +1855,12 @@ rkisp1_ext_params_goc(struct rkisp1_params *params,
 			      RKISP1_CIF_ISP_CTRL_ISP_GAMMA_OUT_ENA);
 }
 
-static void
-rkisp1_ext_params_dpf(struct rkisp1_params *params,
-		      const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_dpf(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_dpf_config *dpf = &block->dpf;
+	const struct rkisp1_ext_params_dpf_config *dpf =
+		(const struct rkisp1_ext_params_dpf_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (dpf->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_DPF_MODE,
@@ -1889,20 +1876,22 @@ rkisp1_ext_params_dpf(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_DPF_MODE_EN);
 }
 
-static void
-rkisp1_ext_params_dpfs(struct rkisp1_params *params,
-		       const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_dpfs(void *dev,
+				   const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_dpf_strength_config *dpfs = &block->dpfs;
+	const struct rkisp1_ext_params_dpf_strength_config *dpfs =
+		(const struct rkisp1_ext_params_dpf_strength_config *)block;
+	struct rkisp1_params *params = dev;
 
 	rkisp1_dpf_strength_config(params, &dpfs->config);
 }
 
-static void
-rkisp1_ext_params_cproc(struct rkisp1_params *params,
-			const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_cproc(void *dev,
+				    const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_cproc_config *cproc = &block->cproc;
+	const struct rkisp1_ext_params_cproc_config *cproc =
+		(const struct rkisp1_ext_params_cproc_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (cproc->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_C_PROC_CTRL,
@@ -1918,11 +1907,12 @@ rkisp1_ext_params_cproc(struct rkisp1_params *params,
 				      RKISP1_CIF_C_PROC_CTR_ENABLE);
 }
 
-static void
-rkisp1_ext_params_ie(struct rkisp1_params *params,
-		     const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_ie(void *dev,
+				 const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_ie_config *ie = &block->ie;
+	const struct rkisp1_ext_params_ie_config *ie =
+		(const struct rkisp1_ext_params_ie_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (ie->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_ie_enable(params, false);
@@ -1936,11 +1926,12 @@ rkisp1_ext_params_ie(struct rkisp1_params *params,
 		rkisp1_ie_enable(params, true);
 }
 
-static void
-rkisp1_ext_params_awbm(struct rkisp1_params *params,
-		       const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_awbm(void *dev,
+				   const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_awb_meas_config *awbm = &block->awbm;
+	const struct rkisp1_ext_params_awb_meas_config *awbm =
+		(const struct rkisp1_ext_params_awb_meas_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (awbm->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		params->ops->awb_meas_enable(params, &awbm->config,
@@ -1956,11 +1947,12 @@ rkisp1_ext_params_awbm(struct rkisp1_params *params,
 					     true);
 }
 
-static void
-rkisp1_ext_params_hstm(struct rkisp1_params *params,
-		       const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_hstm(void *dev,
+				   const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_hst_config *hst = &block->hst;
+	const struct rkisp1_ext_params_hst_config *hst =
+		(const struct rkisp1_ext_params_hst_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (hst->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		params->ops->hst_enable(params, &hst->config, false);
@@ -1974,11 +1966,12 @@ rkisp1_ext_params_hstm(struct rkisp1_params *params,
 		params->ops->hst_enable(params, &hst->config, true);
 }
 
-static void
-rkisp1_ext_params_aecm(struct rkisp1_params *params,
-		       const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_aecm(void *dev,
+				   const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_aec_config *aec = &block->aec;
+	const struct rkisp1_ext_params_aec_config *aec =
+		(const struct rkisp1_ext_params_aec_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (aec->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_EXP_CTRL,
@@ -1994,11 +1987,12 @@ rkisp1_ext_params_aecm(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_EXP_ENA);
 }
 
-static void
-rkisp1_ext_params_afcm(struct rkisp1_params *params,
-		       const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_afcm(void *dev,
+				   const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_afc_config *afc = &block->afc;
+	const struct rkisp1_ext_params_afc_config *afc =
+		(const struct rkisp1_ext_params_afc_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (afc->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_AFM_CTRL,
@@ -2014,11 +2008,12 @@ rkisp1_ext_params_afcm(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_AFM_ENA);
 }
 
-static void rkisp1_ext_params_compand_bls(struct rkisp1_params *params,
-					  const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_compand_bls(void *dev,
+					  const struct v4l2_params_block_header *block)
 {
 	const struct rkisp1_ext_params_compand_bls_config *bls =
-		&block->compand_bls;
+		(const struct rkisp1_ext_params_compand_bls_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (bls->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
@@ -2034,11 +2029,13 @@ static void rkisp1_ext_params_compand_bls(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_COMPAND_CTRL_BLS_ENABLE);
 }
 
-static void rkisp1_ext_params_compand_expand(struct rkisp1_params *params,
-					     const union rkisp1_ext_params_config *block)
+static void
+rkisp1_ext_params_compand_expand(void *dev,
+				 const struct v4l2_params_block_header *block)
 {
 	const struct rkisp1_ext_params_compand_curve_config *curve =
-		&block->compand_curve;
+		(const struct rkisp1_ext_params_compand_curve_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (curve->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
@@ -2054,11 +2051,13 @@ static void rkisp1_ext_params_compand_expand(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_COMPAND_CTRL_EXPAND_ENABLE);
 }
 
-static void rkisp1_ext_params_compand_compress(struct rkisp1_params *params,
-					       const union rkisp1_ext_params_config *block)
+static void
+rkisp1_ext_params_compand_compress(void *dev,
+				   const struct v4l2_params_block_header *block)
 {
 	const struct rkisp1_ext_params_compand_curve_config *curve =
-		&block->compand_curve;
+		(const struct rkisp1_ext_params_compand_curve_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (curve->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_COMPAND_CTRL,
@@ -2074,10 +2073,12 @@ static void rkisp1_ext_params_compand_compress(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_COMPAND_CTRL_COMPRESS_ENABLE);
 }
 
-static void rkisp1_ext_params_wdr(struct rkisp1_params *params,
-				  const union rkisp1_ext_params_config *block)
+static void rkisp1_ext_params_wdr(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct rkisp1_ext_params_wdr_config *wdr = &block->wdr;
+	const struct rkisp1_ext_params_wdr_config *wdr =
+		(const struct rkisp1_ext_params_wdr_config *)block;
+	struct rkisp1_params *params = dev;
 
 	if (wdr->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
 		rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_WDR_CTRL,
@@ -2093,15 +2094,7 @@ static void rkisp1_ext_params_wdr(struct rkisp1_params *params,
 				      RKISP1_CIF_ISP_WDR_CTRL_ENABLE);
 }
 
-typedef void (*rkisp1_block_handler)(struct rkisp1_params *params,
-			     const union rkisp1_ext_params_config *config);
-
-static const struct rkisp1_ext_params_handler {
-	size_t size;
-	rkisp1_block_handler handler;
-	unsigned int group;
-	unsigned int features;
-} rkisp1_ext_params_handlers[] = {
+static const struct v4l2_params_handler rkisp1_ext_params_handlers[] = {
 	[RKISP1_EXT_PARAMS_BLOCK_TYPE_BLS] = {
 		.size		= sizeof(struct rkisp1_ext_params_bls_config),
 		.handler	= rkisp1_ext_params_bls,
@@ -2224,18 +2217,18 @@ static void rkisp1_ext_params_config(struct rkisp1_params *params,
 
 	/* Walk the list of parameter blocks and process them. */
 	while (block_offset < cfg->data_size) {
-		const struct rkisp1_ext_params_handler *block_handler;
-		const union rkisp1_ext_params_config *block;
+		const struct v4l2_params_handler *block_handler;
+		const struct v4l2_params_block_header *block;
 
-		block = (const union rkisp1_ext_params_config *)
+		block = (const struct v4l2_params_block_header *)
 			&cfg->data[block_offset];
-		block_offset += block->header.size;
+		block_offset += block->size;
 
 		/*
 		 * Make sure the block is supported by the platform and in the
 		 * list of groups to configure.
 		 */
-		block_handler = &rkisp1_ext_params_handlers[block->header.type];
+		block_handler = &rkisp1_ext_params_handlers[block->type];
 		if (!(block_handler->group & block_group_mask))
 			continue;
 
@@ -2245,10 +2238,10 @@ static void rkisp1_ext_params_config(struct rkisp1_params *params,
 
 		block_handler->handler(params, block);
 
-		if (block->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE)
-			params->enabled_blocks &= ~BIT(block->header.type);
-		else if (block->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_ENABLE)
-			params->enabled_blocks |= BIT(block->header.type);
+		if (block->flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE)
+			params->enabled_blocks &= ~BIT(block->type);
+		else if (block->flags & RKISP1_EXT_PARAMS_FL_BLOCK_ENABLE)
+			params->enabled_blocks |= BIT(block->type);
 	}
 }
 
@@ -2641,36 +2634,36 @@ static void rkisp1_params_vb2_buf_queue(struct vb2_buffer *vb)
 	spin_unlock_irq(&params->config_lock);
 }
 
+static int
+rkisp1_ext_params_validate_buffer(struct device *dev,
+				  const struct v4l2_params_buffer *buffer)
+{
+	/* Only v1 is supported at the moment. */
+	if (buffer->version != RKISP1_EXT_PARAM_BUFFER_V1) {
+		dev_dbg(dev, "Unsupported extensible format version: %u\n",
+			buffer->version);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int rkisp1_params_prepare_ext_params(struct rkisp1_params *params,
 					    struct vb2_buffer *vb)
 {
 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
 	struct rkisp1_params_buffer *params_buf = to_rkisp1_params_buffer(vbuf);
-	size_t header_size = offsetof(struct rkisp1_ext_params_cfg, data);
 	struct rkisp1_ext_params_cfg *cfg = params_buf->cfg;
 	size_t payload_size = vb2_get_plane_payload(vb, 0);
 	struct rkisp1_ext_params_cfg *usr_cfg =
 		vb2_plane_vaddr(&vbuf->vb2_buf, 0);
-	size_t block_offset = 0;
-	size_t cfg_size;
-
-	/*
-	 * Validate the buffer payload size before copying the parameters. The
-	 * payload has to be smaller than the destination buffer size and larger
-	 * than the header size.
-	 */
-	if (payload_size > params->metafmt->buffersize) {
-		dev_dbg(params->rkisp1->dev,
-			"Too large buffer payload size %zu\n", payload_size);
-		return -EINVAL;
-	}
+	int ret;
 
-	if (payload_size < header_size) {
-		dev_dbg(params->rkisp1->dev,
-			"Buffer payload %zu smaller than header size %zu\n",
-			payload_size, header_size);
-		return -EINVAL;
-	}
+	ret = v4l2_params_buffer_validate(params->rkisp1->dev, vb,
+					  params->metafmt->buffersize,
+					  rkisp1_ext_params_validate_buffer);
+	if (ret)
+		return ret;
 
 	/*
 	 * Copy the parameters buffer to the internal scratch buffer to avoid
@@ -2678,71 +2671,11 @@ static int rkisp1_params_prepare_ext_params(struct rkisp1_params *params,
 	 */
 	memcpy(cfg, usr_cfg, payload_size);
 
-	/* Only v1 is supported at the moment. */
-	if (cfg->version != RKISP1_EXT_PARAM_BUFFER_V1) {
-		dev_dbg(params->rkisp1->dev,
-			"Unsupported extensible format version: %u\n",
-			cfg->version);
-		return -EINVAL;
-	}
-
-	/* Validate the size reported in the parameters buffer header. */
-	cfg_size = header_size + cfg->data_size;
-	if (cfg_size != payload_size) {
-		dev_dbg(params->rkisp1->dev,
-			"Data size %zu different than buffer payload size %zu\n",
-			cfg_size, payload_size);
-		return -EINVAL;
-	}
-
-	/* Walk the list of parameter blocks and validate them. */
-	cfg_size = cfg->data_size;
-	while (cfg_size >= sizeof(struct rkisp1_ext_params_block_header)) {
-		const struct rkisp1_ext_params_block_header *block;
-		const struct rkisp1_ext_params_handler *handler;
-
-		block = (const struct rkisp1_ext_params_block_header *)
-			&cfg->data[block_offset];
-
-		if (block->type >= ARRAY_SIZE(rkisp1_ext_params_handlers)) {
-			dev_dbg(params->rkisp1->dev,
-				"Invalid parameters block type\n");
-			return -EINVAL;
-		}
-
-		if (block->size > cfg_size) {
-			dev_dbg(params->rkisp1->dev,
-				"Premature end of parameters data\n");
-			return -EINVAL;
-		}
-
-		if ((block->flags & (RKISP1_EXT_PARAMS_FL_BLOCK_ENABLE |
-				     RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE)) ==
-		   (RKISP1_EXT_PARAMS_FL_BLOCK_ENABLE |
-		    RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE)) {
-			dev_dbg(params->rkisp1->dev,
-				"Invalid parameters block flags\n");
-			return -EINVAL;
-		}
-
-		handler = &rkisp1_ext_params_handlers[block->type];
-		if (block->size != handler->size) {
-			dev_dbg(params->rkisp1->dev,
-				"Invalid parameters block size\n");
-			return -EINVAL;
-		}
-
-		block_offset += block->size;
-		cfg_size -= block->size;
-	}
-
-	if (cfg_size) {
-		dev_dbg(params->rkisp1->dev,
-			"Unexpected data after the parameters buffer end\n");
-		return -EINVAL;
-	}
-
-	return 0;
+	return v4l2_params_blocks_validate(params->rkisp1->dev,
+					   (struct v4l2_params_buffer *)cfg,
+					   rkisp1_ext_params_handlers,
+					   ARRAY_SIZE(rkisp1_ext_params_handlers),
+					   NULL);
 }
 
 static int rkisp1_params_vb2_buf_prepare(struct vb2_buffer *vb)
@@ -2842,7 +2775,7 @@ static int rkisp1_params_ctrl_init(struct rkisp1_params *params)
 	v4l2_ctrl_handler_init(&params->ctrls, 1);
 
 	for (unsigned int i = 0; i < ARRAY_SIZE(rkisp1_ext_params_handlers); i++) {
-		const struct rkisp1_ext_params_handler *block_handler;
+		const struct v4l2_params_handler *block_handler;
 
 		block_handler = &rkisp1_ext_params_handlers[i];
 		ctrl_config.max |= BIT(i);

-- 
2.50.1


_______________________________________________
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[PATCH v3 7/8] media: amlogic-c3: Use v4l2-params for validation

[Jacopo Mondi]

Convert c3-ispa-params.c to use the new types fro block handlers
defined in v4l2-params.h and use the new helpers from v4l2-params.c
to remove boilerplate code from the driver.

Reviewed-by: Keke Li <keke.li@amlogic.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 .../media/platform/amlogic/c3/isp/c3-isp-params.c  | 263 ++++++++-------------
 1 file changed, 94 insertions(+), 169 deletions(-)

diff --git a/drivers/media/platform/amlogic/c3/isp/c3-isp-params.c b/drivers/media/platform/amlogic/c3/isp/c3-isp-params.c
index c80667dd766210d2b2e1ee60c8254a5814b9d81b..259cb354ffddf4a1195422dfd9b3ba24c79607fc 100644
--- a/drivers/media/platform/amlogic/c3/isp/c3-isp-params.c
+++ b/drivers/media/platform/amlogic/c3/isp/c3-isp-params.c
@@ -9,64 +9,26 @@
 
 #include <media/v4l2-ioctl.h>
 #include <media/v4l2-mc.h>
+#include <media/v4l2-params.h>
 #include <media/videobuf2-vmalloc.h>
 
 #include "c3-isp-common.h"
 #include "c3-isp-regs.h"
 
-/*
- * union c3_isp_params_block - Generalisation of a parameter block
- *
- * This union allows the driver to treat a block as a generic struct to this
- * union and safely access the header and block-specific struct without having
- * to resort to casting. The header member is accessed first, and the type field
- * checked which allows the driver to determine which of the other members
- * should be used.
- *
- * @header:		The shared header struct embedded as the first member
- *			of all the possible other members. This member would be
- *			accessed first and the type field checked to determine
- *			which of the other members should be accessed.
- * @awb_gains:		For header.type == C3_ISP_PARAMS_BLOCK_AWB_GAINS
- * @awb_cfg:		For header.type == C3_ISP_PARAMS_BLOCK_AWB_CONFIG
- * @ae_cfg:		For header.type == C3_ISP_PARAMS_BLOCK_AE_CONFIG
- * @af_cfg:		For header.type == C3_ISP_PARAMS_BLOCK_AF_CONFIG
- * @pst_gamma:		For header.type == C3_ISP_PARAMS_BLOCK_PST_GAMMA
- * @ccm:		For header.type == C3_ISP_PARAMS_BLOCK_CCM
- * @csc:		For header.type == C3_ISP_PARAMS_BLOCK_CSC
- * @blc:		For header.type == C3_ISP_PARAMS_BLOCK_BLC
- */
-union c3_isp_params_block {
-	struct c3_isp_params_block_header header;
-	struct c3_isp_params_awb_gains awb_gains;
-	struct c3_isp_params_awb_config awb_cfg;
-	struct c3_isp_params_ae_config ae_cfg;
-	struct c3_isp_params_af_config af_cfg;
-	struct c3_isp_params_pst_gamma pst_gamma;
-	struct c3_isp_params_ccm ccm;
-	struct c3_isp_params_csc csc;
-	struct c3_isp_params_blc blc;
-};
-
-typedef void (*c3_isp_block_handler)(struct c3_isp_device *isp,
-				     const union c3_isp_params_block *block);
-
-struct c3_isp_params_handler {
-	size_t size;
-	c3_isp_block_handler handler;
-};
-
 #define to_c3_isp_params_buffer(vbuf) \
 	container_of(vbuf, struct c3_isp_params_buffer, vb)
 
 /* Hardware configuration */
 
-static void c3_isp_params_cfg_awb_gains(struct c3_isp_device *isp,
-					const union c3_isp_params_block *block)
+static void
+c3_isp_params_cfg_awb_gains(void *dev,
+			    const struct v4l2_params_block_header *block)
 {
-	const struct c3_isp_params_awb_gains *awb_gains = &block->awb_gains;
+	const struct c3_isp_params_awb_gains *awb_gains =
+		(const struct c3_isp_params_awb_gains *)block;
+	struct c3_isp_device *isp = dev;
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
 		c3_isp_update_bits(isp, ISP_TOP_BEO_CTRL,
 				   ISP_TOP_BEO_CTRL_WB_EN_MASK,
 				   ISP_TOP_BEO_CTRL_WB_DIS);
@@ -89,7 +51,7 @@ static void c3_isp_params_cfg_awb_gains(struct c3_isp_device *isp,
 			   ISP_LSWB_WB_GAIN2_IR_GAIN_MASK,
 			   ISP_LSWB_WB_GAIN2_IR_GAIN(awb_gains->gb_gain));
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
 		c3_isp_update_bits(isp, ISP_TOP_BEO_CTRL,
 				   ISP_TOP_BEO_CTRL_WB_EN_MASK,
 				   ISP_TOP_BEO_CTRL_WB_EN);
@@ -151,12 +113,15 @@ static void c3_isp_params_awb_cood(struct c3_isp_device *isp,
 			     ISP_AWB_IDX_DATA_VIDX_DATA(cfg->vert_coord[i]));
 }
 
-static void c3_isp_params_cfg_awb_config(struct c3_isp_device *isp,
-					 const union c3_isp_params_block *block)
+static void
+c3_isp_params_cfg_awb_config(void *dev,
+			     const struct v4l2_params_block_header *block)
 {
-	const struct c3_isp_params_awb_config *awb_cfg = &block->awb_cfg;
+	const struct c3_isp_params_awb_config *awb_cfg =
+		(const struct c3_isp_params_awb_config *)block;
+	struct c3_isp_device *isp = dev;
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
 		c3_isp_update_bits(isp, ISP_TOP_3A_STAT_CRTL,
 				   ISP_TOP_3A_STAT_CRTL_AWB_STAT_EN_MASK,
 				   ISP_TOP_3A_STAT_CRTL_AWB_STAT_DIS);
@@ -205,7 +170,7 @@ static void c3_isp_params_cfg_awb_config(struct c3_isp_device *isp,
 	c3_isp_params_awb_wt(isp, awb_cfg);
 	c3_isp_params_awb_cood(isp, awb_cfg);
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
 		c3_isp_update_bits(isp, ISP_TOP_3A_STAT_CRTL,
 				   ISP_TOP_3A_STAT_CRTL_AWB_STAT_EN_MASK,
 				   ISP_TOP_3A_STAT_CRTL_AWB_STAT_EN);
@@ -268,12 +233,15 @@ static void c3_isp_params_ae_cood(struct c3_isp_device *isp,
 			     ISP_AE_IDX_DATA_VIDX_DATA(cfg->vert_coord[i]));
 }
 
-static void c3_isp_params_cfg_ae_config(struct c3_isp_device *isp,
-					const union c3_isp_params_block *block)
+static void
+c3_isp_params_cfg_ae_config(void *dev,
+			    const struct v4l2_params_block_header *block)
 {
-	const struct c3_isp_params_ae_config *ae_cfg = &block->ae_cfg;
+	const struct c3_isp_params_ae_config *ae_cfg =
+		(const struct c3_isp_params_ae_config *)block;
+	struct c3_isp_device *isp = dev;
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
 		c3_isp_update_bits(isp, ISP_TOP_3A_STAT_CRTL,
 				   ISP_TOP_3A_STAT_CRTL_AE_STAT_EN_MASK,
 				   ISP_TOP_3A_STAT_CRTL_AE_STAT_DIS);
@@ -303,7 +271,7 @@ static void c3_isp_params_cfg_ae_config(struct c3_isp_device *isp,
 	c3_isp_params_ae_wt(isp, ae_cfg);
 	c3_isp_params_ae_cood(isp, ae_cfg);
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
 		c3_isp_update_bits(isp, ISP_TOP_3A_STAT_CRTL,
 				   ISP_TOP_3A_STAT_CRTL_AE_STAT_EN_MASK,
 				   ISP_TOP_3A_STAT_CRTL_AE_STAT_EN);
@@ -326,12 +294,15 @@ static void c3_isp_params_af_cood(struct c3_isp_device *isp,
 			     ISP_AF_IDX_DATA_VIDX_DATA(cfg->vert_coord[i]));
 }
 
-static void c3_isp_params_cfg_af_config(struct c3_isp_device *isp,
-					const union c3_isp_params_block *block)
+static void
+c3_isp_params_cfg_af_config(void *dev,
+			    const struct v4l2_params_block_header *block)
 {
-	const struct c3_isp_params_af_config *af_cfg = &block->af_cfg;
+	const struct c3_isp_params_af_config *af_cfg =
+		(const struct c3_isp_params_af_config *)block;
+	struct c3_isp_device *isp = dev;
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
 		c3_isp_update_bits(isp, ISP_TOP_3A_STAT_CRTL,
 				   ISP_TOP_3A_STAT_CRTL_AF_STAT_EN_MASK,
 				   ISP_TOP_3A_STAT_CRTL_AF_STAT_DIS);
@@ -351,20 +322,23 @@ static void c3_isp_params_cfg_af_config(struct c3_isp_device *isp,
 
 	c3_isp_params_af_cood(isp, af_cfg);
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
 		c3_isp_update_bits(isp, ISP_TOP_3A_STAT_CRTL,
 				   ISP_TOP_3A_STAT_CRTL_AF_STAT_EN_MASK,
 				   ISP_TOP_3A_STAT_CRTL_AF_STAT_EN);
 }
 
-static void c3_isp_params_cfg_pst_gamma(struct c3_isp_device *isp,
-					const union c3_isp_params_block *block)
+static void
+c3_isp_params_cfg_pst_gamma(void *dev,
+			    const struct v4l2_params_block_header *block)
 {
-	const struct c3_isp_params_pst_gamma *gm = &block->pst_gamma;
+	const struct c3_isp_params_pst_gamma *gm =
+		(const struct c3_isp_params_pst_gamma *)block;
+	struct c3_isp_device *isp = dev;
 	unsigned int base;
 	unsigned int i;
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
 		c3_isp_update_bits(isp, ISP_TOP_BED_CTRL,
 				   ISP_TOP_BED_CTRL_PST_GAMMA_EN_MASK,
 				   ISP_TOP_BED_CTRL_PST_GAMMA_DIS);
@@ -393,19 +367,21 @@ static void c3_isp_params_cfg_pst_gamma(struct c3_isp_device *isp,
 		}
 	}
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
 		c3_isp_update_bits(isp, ISP_TOP_BED_CTRL,
 				   ISP_TOP_BED_CTRL_PST_GAMMA_EN_MASK,
 				   ISP_TOP_BED_CTRL_PST_GAMMA_EN);
 }
 
 /* Configure 3 x 3 ccm matrix */
-static void c3_isp_params_cfg_ccm(struct c3_isp_device *isp,
-				  const union c3_isp_params_block *block)
+static void c3_isp_params_cfg_ccm(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct c3_isp_params_ccm *ccm = &block->ccm;
+	const struct c3_isp_params_ccm *ccm =
+		(const struct c3_isp_params_ccm *)block;
+	struct c3_isp_device *isp = dev;
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
 		c3_isp_update_bits(isp, ISP_TOP_BED_CTRL,
 				   ISP_TOP_BED_CTRL_CCM_EN_MASK,
 				   ISP_TOP_BED_CTRL_CCM_DIS);
@@ -442,19 +418,21 @@ static void c3_isp_params_cfg_ccm(struct c3_isp_device *isp,
 			   ISP_CCM_MTX_22_23_RS_MTX_22_MASK,
 			   ISP_CCM_MTX_22_23_RS_MTX_22(ccm->matrix[2][2]));
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
 		c3_isp_update_bits(isp, ISP_TOP_BED_CTRL,
 				   ISP_TOP_BED_CTRL_CCM_EN_MASK,
 				   ISP_TOP_BED_CTRL_CCM_EN);
 }
 
 /* Configure color space conversion matrix parameters */
-static void c3_isp_params_cfg_csc(struct c3_isp_device *isp,
-				  const union c3_isp_params_block *block)
+static void c3_isp_params_cfg_csc(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct c3_isp_params_csc *csc = &block->csc;
+	const struct c3_isp_params_csc *csc =
+		(const struct c3_isp_params_csc *)block;
+	struct c3_isp_device *isp = dev;
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
 		c3_isp_update_bits(isp, ISP_TOP_BED_CTRL,
 				   ISP_TOP_BED_CTRL_CM0_EN_MASK,
 				   ISP_TOP_BED_CTRL_CM0_DIS);
@@ -491,19 +469,21 @@ static void c3_isp_params_cfg_csc(struct c3_isp_device *isp,
 			   ISP_CM0_COEF22_OUP_OFST0_MTX_22_MASK,
 			   ISP_CM0_COEF22_OUP_OFST0_MTX_22(csc->matrix[2][2]));
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
 		c3_isp_update_bits(isp, ISP_TOP_BED_CTRL,
 				   ISP_TOP_BED_CTRL_CM0_EN_MASK,
 				   ISP_TOP_BED_CTRL_CM0_EN);
 }
 
 /* Set blc offset of each color channel */
-static void c3_isp_params_cfg_blc(struct c3_isp_device *isp,
-				  const union c3_isp_params_block *block)
+static void c3_isp_params_cfg_blc(void *dev,
+				  const struct v4l2_params_block_header *block)
 {
-	const struct c3_isp_params_blc *blc = &block->blc;
+	const struct c3_isp_params_blc *blc =
+		(const struct c3_isp_params_blc *)block;
+	struct c3_isp_device *isp = dev;
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_DISABLE) {
 		c3_isp_update_bits(isp, ISP_TOP_BEO_CTRL,
 				   ISP_TOP_BEO_CTRL_BLC_EN_MASK,
 				   ISP_TOP_BEO_CTRL_BLC_DIS);
@@ -517,13 +497,13 @@ static void c3_isp_params_cfg_blc(struct c3_isp_device *isp,
 		     ISP_LSWB_BLC_OFST1_GB_OFST(blc->gb_ofst) |
 		     ISP_LSWB_BLC_OFST1_B_OFST(blc->b_ofst));
 
-	if (block->header.flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
+	if (block->flags & C3_ISP_PARAMS_BLOCK_FL_ENABLE)
 		c3_isp_update_bits(isp, ISP_TOP_BEO_CTRL,
 				   ISP_TOP_BEO_CTRL_BLC_EN_MASK,
 				   ISP_TOP_BEO_CTRL_BLC_EN);
 }
 
-static const struct c3_isp_params_handler c3_isp_params_handlers[] = {
+static const struct v4l2_params_handler c3_isp_params_handlers[] = {
 	[C3_ISP_PARAMS_BLOCK_AWB_GAINS] = {
 		.size = sizeof(struct c3_isp_params_awb_gains),
 		.handler = c3_isp_params_cfg_awb_gains,
@@ -568,16 +548,16 @@ static void c3_isp_params_cfg_blocks(struct c3_isp_params *params)
 
 	/* Walk the list of parameter blocks and process them */
 	while (block_offset < config->data_size) {
-		const struct c3_isp_params_handler *block_handler;
-		const union c3_isp_params_block *block;
+		const struct v4l2_params_handler *block_handler;
+		const struct v4l2_params_block_header *block;
 
-		block = (const union c3_isp_params_block *)
+		block = (const struct v4l2_params_block_header *)
 			 &config->data[block_offset];
 
-		block_handler = &c3_isp_params_handlers[block->header.type];
+		block_handler = &c3_isp_params_handlers[block->type];
 		block_handler->handler(params->isp, block);
 
-		block_offset += block->header.size;
+		block_offset += block->size;
 	}
 }
 
@@ -766,31 +746,35 @@ static void c3_isp_params_vb2_buf_queue(struct vb2_buffer *vb)
 	list_add_tail(&buf->list, &params->pending);
 }
 
+static int
+c3_isp_params_validate_buffer(struct device *dev,
+			      const struct v4l2_params_buffer *buffer)
+{
+	/* Only v0 is supported at the moment */
+	if (buffer->version != C3_ISP_PARAMS_BUFFER_V0) {
+		dev_dbg(dev, "Invalid params buffer version: %u\n",
+			buffer->version);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int c3_isp_params_vb2_buf_prepare(struct vb2_buffer *vb)
 {
 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
 	struct c3_isp_params_buffer *buf = to_c3_isp_params_buffer(vbuf);
 	struct c3_isp_params *params = vb2_get_drv_priv(vb->vb2_queue);
-	struct c3_isp_params_cfg *cfg = buf->cfg;
 	struct c3_isp_params_cfg *usr_cfg = vb2_plane_vaddr(vb, 0);
 	size_t payload_size = vb2_get_plane_payload(vb, 0);
-	size_t header_size = offsetof(struct c3_isp_params_cfg, data);
-	size_t block_offset = 0;
-	size_t cfg_size;
-
-	/* Payload size can't be greater than the destination buffer size */
-	if (payload_size > params->vfmt.fmt.meta.buffersize) {
-		dev_dbg(params->isp->dev,
-			"Payload size is too large: %zu\n", payload_size);
-		return -EINVAL;
-	}
+	struct c3_isp_params_cfg *cfg = buf->cfg;
+	int ret;
 
-	/* Payload size can't be smaller than the header size */
-	if (payload_size < header_size) {
-		dev_dbg(params->isp->dev,
-			"Payload size is too small: %zu\n", payload_size);
-		return -EINVAL;
-	}
+	ret = v4l2_params_buffer_validate(params->isp->dev, vb,
+					  params->vfmt.fmt.meta.buffersize,
+					  c3_isp_params_validate_buffer);
+	if (ret)
+		return ret;
 
 	/*
 	 * Use the internal scratch buffer to avoid userspace modifying
@@ -798,70 +782,11 @@ static int c3_isp_params_vb2_buf_prepare(struct vb2_buffer *vb)
 	 */
 	memcpy(cfg, usr_cfg, payload_size);
 
-	/* Only v0 is supported at the moment */
-	if (cfg->version != C3_ISP_PARAMS_BUFFER_V0) {
-		dev_dbg(params->isp->dev,
-			"Invalid params buffer version: %u\n", cfg->version);
-		return -EINVAL;
-	}
-
-	/* Validate the size reported in the parameter buffer header */
-	cfg_size = header_size + cfg->data_size;
-	if (cfg_size != payload_size) {
-		dev_dbg(params->isp->dev,
-			"Data size %zu and payload size %zu are different\n",
-			cfg_size, payload_size);
-		return -EINVAL;
-	}
-
-	/* Walk the list of parameter blocks and validate them */
-	cfg_size = cfg->data_size;
-	while (cfg_size >= sizeof(struct c3_isp_params_block_header)) {
-		const struct c3_isp_params_block_header *block;
-		const struct c3_isp_params_handler *handler;
-
-		block = (struct c3_isp_params_block_header *)
-			&cfg->data[block_offset];
-
-		if (block->type >= ARRAY_SIZE(c3_isp_params_handlers)) {
-			dev_dbg(params->isp->dev,
-				"Invalid params block type\n");
-			return -EINVAL;
-		}
-
-		if (block->size > cfg_size) {
-			dev_dbg(params->isp->dev,
-				"Block size is greater than cfg size\n");
-			return -EINVAL;
-		}
-
-		if ((block->flags & (C3_ISP_PARAMS_BLOCK_FL_ENABLE |
-				     C3_ISP_PARAMS_BLOCK_FL_DISABLE)) ==
-		    (C3_ISP_PARAMS_BLOCK_FL_ENABLE |
-		     C3_ISP_PARAMS_BLOCK_FL_DISABLE)) {
-			dev_dbg(params->isp->dev,
-				"Invalid parameters block flags\n");
-			return -EINVAL;
-		}
-
-		handler = &c3_isp_params_handlers[block->type];
-		if (block->size != handler->size) {
-			dev_dbg(params->isp->dev,
-				"Invalid params block size\n");
-			return -EINVAL;
-		}
-
-		block_offset += block->size;
-		cfg_size -= block->size;
-	}
-
-	if (cfg_size) {
-		dev_dbg(params->isp->dev,
-			"Unexpected data after the params buffer end\n");
-		return -EINVAL;
-	}
-
-	return 0;
+	return v4l2_params_blocks_validate(params->isp->dev,
+					   (struct v4l2_params_buffer *)cfg,
+					   c3_isp_params_handlers,
+					   ARRAY_SIZE(c3_isp_params_handlers),
+					   NULL);
 }
 
 static int c3_isp_params_vb2_buf_init(struct vb2_buffer *vb)

-- 
2.50.1


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[PATCH v3 8/8] media: Documentation: kapi: Add v4l2 extensible parameters

[Jacopo Mondi]

Add to the driver-api documentation the v4l2-params.h types and
helpers documentation.

Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 Documentation/driver-api/media/v4l2-core.rst   | 1 +
 Documentation/driver-api/media/v4l2-params.rst | 5 +++++
 MAINTAINERS                                    | 1 +
 3 files changed, 7 insertions(+)

diff --git a/Documentation/driver-api/media/v4l2-core.rst b/Documentation/driver-api/media/v4l2-core.rst
index ad987c34ad2a8460bb95e97adc4d850d624e0b81..2d7793298c6a2046bdd59b185a411e092b659d52 100644
--- a/Documentation/driver-api/media/v4l2-core.rst
+++ b/Documentation/driver-api/media/v4l2-core.rst
@@ -27,3 +27,4 @@ Video4Linux devices
     v4l2-common
     v4l2-tveeprom
     v4l2-jpeg
+    v4l2-params
diff --git a/Documentation/driver-api/media/v4l2-params.rst b/Documentation/driver-api/media/v4l2-params.rst
new file mode 100644
index 0000000000000000000000000000000000000000..8d2a5f004d21dfc3a81255cabbc6b7cce588db71
--- /dev/null
+++ b/Documentation/driver-api/media/v4l2-params.rst
@@ -0,0 +1,5 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+V4L2 extensible parameters kAPI
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+.. kernel-doc:: include/media/v4l2-params.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 008f984c0769691f6ddec8d8f0f461fde056ddb3..44598a823f084e98a9b2d2e21881665d1ab64908 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26384,6 +26384,7 @@ V4L2 EXTENSIBLE PARAMETERS FORMAT
 M:	Jacopo Mondi <jacopo.mondi@ideasonboard.com>
 L:	linux-media@vger.kernel.org
 S:	Maintained
+F:	Documentation/driver-api/media/v4l2-params.rst
 F:	Documentation/userspace-api/media/v4l/extensible-parameters.rst
 F:	drivers/media/v4l2-core/v4l2-params.c
 F:	include/media/v4l2-params.h

-- 
2.50.1


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Re: [PATCH v3 1/8] media: uapi: Introduce V4L2 extensible params

[Sakari Ailus]

Hi Jacopo,

Thank you for working on this.

On Tue, Aug 19, 2025 at 04:54:42PM +0200, Jacopo Mondi wrote:
> Introduce v4l2-extensible-params.h in the Linux kernel uAPI.
> 
> The header defines two types that all drivers that use the extensible
> parameters format for ISP configuration shall use to build their own
> format versions.
> 
> The newly introduce type v4l2_params_block represent the
> header to be prepend to each ISP configuration block and the
> v4l2_params_buffer type represent the base type for the configuration
> parameters buffer.
> 
> The v4l2_params_buffer represents the container for the ISP
> configuration data block. The generic type is defined with a 0-sized
> data block that specific ISP implementation shall properly size
> according to their capabilities.
> 
> [Add v4l2_params_buffer_size()]
> 
> Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
> Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
> Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> ---
>  MAINTAINERS                                       |   6 +
>  include/uapi/linux/media/v4l2-extensible-params.h | 144 ++++++++++++++++++++++
>  2 files changed, 150 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index fe168477caa45799dfe07de2f54de6d6a1ce0615..67216d1e92d7ac81617bb3c4329e4096aa205706 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -26380,6 +26380,12 @@ F:	drivers/media/i2c/vd55g1.c
>  F:	drivers/media/i2c/vd56g3.c
>  F:	drivers/media/i2c/vgxy61.c
>  
> +V4L2 EXTENSIBLE PARAMETERS FORMAT
> +M:	Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> +L:	linux-media@vger.kernel.org
> +S:	Maintained
> +F:	include/uapi/linux/media/v4l2-extensible-params.h
> +
>  VF610 NAND DRIVER
>  M:	Stefan Agner <stefan@agner.ch>
>  L:	linux-mtd@lists.infradead.org
> diff --git a/include/uapi/linux/media/v4l2-extensible-params.h b/include/uapi/linux/media/v4l2-extensible-params.h
> new file mode 100644
> index 0000000000000000000000000000000000000000..ace89299a4b37e428c0bc9a72fbc079b1dcda91a
> --- /dev/null
> +++ b/include/uapi/linux/media/v4l2-extensible-params.h
> @@ -0,0 +1,144 @@
> +/* SPDX-License-Identifier: ((GPL-2.0+ WITH Linux-syscall-note) OR MIT) */
> +/*
> + * Video4Linux2 extensible configuration parameters base types
> + *
> + * Copyright (C) 2025 Ideas On Board Oy
> + * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> + */
> +
> +#ifndef _UAPI_V4L2_PARAMS_H_
> +#define _UAPI_V4L2_PARAMS_H_
> +
> +#include <linux/types.h>
> +
> +#define V4L2_PARAMS_FL_BLOCK_DISABLE	(1U << 0)
> +#define V4L2_PARAMS_FL_BLOCK_ENABLE	(1U << 1)
> +
> +/*
> + * Reserve the first 8 bits for V4L2_PARAMS_FL_* flag. Platform-specific flags
> + * should be defined as:
> + * #define PLATFORM_SPECIFIC_FLAG0	((1U << V4L2_PARAMS_FL_PLATFORM_FLAGS(0))
> + * #define PLATFORM_SPECIFIC_FLAG1	((1U << V4L2_PARAMS_FL_PLATFORM_FLAGS(1))

How many bits are you shifting left here again?

> + */
> +#define V4L2_PARAMS_FL_PLATFORM_FLAGS(n)	((n) << 8)

n really needs to be unsigned.

> +
> +/**
> + * struct v4l2_params_block_header - V4L2 extensible parameters block header
> + *
> + * This structure represents the common part of all the ISP configuration
> + * blocks. Each parameters block shall embed an instance of this structure type
> + * as its first member, followed by the block-specific configuration data. The
> + * driver inspects this common header to discern the block type and its size and
> + * properly handle the block content by casting it to the correct block-specific
> + * type.
> + *
> + * The @type field is one of the values enumerated by each platform-specific ISP
> + * block types which specifies how the data should be interpreted by the driver.
> + * The @size field specifies the size of the parameters block and is used by the
> + * driver for validation purposes.
> + *
> + * The @flags field is a bitmask of per-block flags V4L2_PARAMS_FL_* and
> + * platform-specific flags specified by the platform-specific header.
> + *
> + * Documentation of the platform-specific flags handling is specified by the
> + * platform-specific block header type:
> + *
> + * - Rockchip RkISP1: :c:type:`rkisp1_ext_params_block_type`
> + * - Amlogic C3: :c:type:`c3_isp_params_block_type`
> + *
> + * Userspace is responsible for correctly populating the parameters block header
> + * fields (@type, @flags and @size) and the block-specific parameters.
> + *
> + * @type: The parameters block type (platform-specific)
> + * @flags: A bitmask of block flags (platform-specific)
> + * @size: Size (in bytes) of the parameters block, including this header
> + */
> +struct v4l2_params_block_header {
> +	__u16 type;
> +	__u16 flags;
> +	__u32 size;
> +} __attribute__((aligned(8)));
> +
> +/**
> + * v4l2_params_buffer_size - Calculate size of v4l2_params_buffer for a platform
> + *
> + * Users of the v4l2 extensible parameters will have differing sized data arrays
> + * depending on their specific parameter buffers. Drivers and userspace will
> + * need to be able to calculate the appropriate size of the struct to
> + * accommodate all ISP configuration blocks provided by the platform.
> + * This macro provides a convenient tool for the calculation.
> + *
> + * Each driver shall provide a definition of their extensible parameters
> + * implementation data buffer size. As an example:
> + *
> + * #define PLATFORM_BLOCKS_MAX_SIZE		\
> + *	sizeof(platform_block_0)	+	\
> + *	sizeof(platform_block_1)
> + *
> + * #define PLATFORM_BUFFER_SIZE			\
> + *	v4l2_params_buffer_size(PLATFORM_BLOCKS_MAX_SIZE)
> + *
> + * Drivers are then responsible for allocating buffers of the proper size
> + * by assigning PLATFORM_BUFFER_SIZE to the per-plane size of the videobuf2
> + * .queue_setup() operation and userspace shall use PLATFORM_BUFFER_SIZE
> + * when populating the ISP configuration data buffer.
> + *
> + * @max_params_size: The total size of the ISP configuration blocks
> + */
> +#define v4l2_params_buffer_size(max_params_size) \
> +	(offsetof(struct v4l2_params_buffer, data) + (max_params_size))
> +
> +/**
> + * struct v4l2_params_buffer - V4L2 extensible parameters configuration
> + *
> + * This struct contains the configuration parameters of the ISP algorithms,
> + * serialized by userspace into a data buffer. Each configuration parameter
> + * block is represented by a block-specific structure which contains a
> + * :c:type:`v4l2_params_block_header` entry as first member. Userspace populates
> + * the @data buffer with configuration parameters for the blocks that it intends
> + * to configure. As a consequence, the data buffer effective size changes
> + * according to the number of ISP blocks that userspace intends to configure and
> + * is set by userspace in the @data_size field.
> + *
> + * The parameters buffer is versioned by the @version field to allow modifying
> + * and extending its definition. Userspace shall populate the @version field to
> + * inform the driver about the version it intends to use. The driver will parse
> + * and handle the @data buffer according to the data layout specific to the
> + * indicated version and return an error if the desired version is not
> + * supported.
> + *
> + * For each ISP block that userspace wants to configure, a block-specific
> + * structure is appended to the @data buffer, one after the other without gaps
> + * in between nor overlaps. Userspace shall populate the @data_size field with
> + * the effective size, in bytes, of the @data buffer.
> + *
> + * Drivers shall take care of properly sizing of the extensible parameters
> + * buffer @data array. The v4l2_params_buffer type is defined with a
> + * flexible-array-member at the end, which resolves to a size of 0 bytes when
> + * inspected with sizeof(struct v4l2_params_buffer). This of course is not
> + * suitable for neither buffer allocation in the kernel driver nor for proper
> + * handling in userspace of the @data buffer it has to populate.
> + *
> + * Drivers using this type in their userspace API definition are responsible
> + * for providing the exact definition of the @data buffer size using the
> + * v4l2_params_buffer_size() macro. The size shall be used
> + * by the driver for buffers allocation and by userspace for populating the
> + * @data buffer before queueing it to the driver
> + *
> + * Drivers that were already using extensible-parameters before the introduction
> + * of this file define their own type-convertible implementation of this
> + * type, see:
> + * - Rockchip RkISP1: :c:type:`rkisp1_ext_params_cfg`
> + * - Amlogic C3: :c:type:`c3_isp_params_cfg`
> + *
> + * @version: The parameters buffer version (platform-specific)
> + * @data_size: The configuration data effective size, excluding this header
> + * @data: The configuration data
> + */
> +struct v4l2_params_buffer {
> +	__u32 version;
> +	__u32 data_size;
> +	__u8 data[];

Would __attribute__((__counted_by__(data_size))) be problematic here?

Perhaps not now but it could be added later on?

> +};
> +
> +#endif /* _UAPI_V4L2_PARAMS_H_ */
> 

-- 
Kind regards,

Sakari Ailus

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Re: [PATCH v3 5/8] media: v4l2-common: Introduce v4l2-params.c

[Sakari Ailus]

Hi Jacopo,

In the subject:

s/common/params/

On Tue, Aug 19, 2025 at 04:54:46PM +0200, Jacopo Mondi wrote:
> Add to the v4l2 framework an helper function to support drivers
> when validating a buffer of extensible parameters.
> 
> Introduce new types in include/media/v4l2-params.h that drivers shall
> use in order to comply with the v4l2-params validation procedure, and
> add a helper functions to v4l2-params.c to perform block and buffer
> validation.
> 
> Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
> Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> ---
>  MAINTAINERS                           |   2 +
>  drivers/media/v4l2-core/Makefile      |   3 +-
>  drivers/media/v4l2-core/v4l2-params.c | 123 +++++++++++++++++++++++++
>  include/media/v4l2-params.h           | 165 ++++++++++++++++++++++++++++++++++
>  4 files changed, 292 insertions(+), 1 deletion(-)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 91df04e5d9022ccf2aea4445247369a8b86a4264..008f984c0769691f6ddec8d8f0f461fde056ddb3 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -26385,6 +26385,8 @@ M:	Jacopo Mondi <jacopo.mondi@ideasonboard.com>
>  L:	linux-media@vger.kernel.org
>  S:	Maintained
>  F:	Documentation/userspace-api/media/v4l/extensible-parameters.rst
> +F:	drivers/media/v4l2-core/v4l2-params.c
> +F:	include/media/v4l2-params.h
>  F:	include/uapi/linux/media/v4l2-extensible-params.h
>  
>  VF610 NAND DRIVER
> diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
> index 2177b9d63a8ffc1127c5a70118249a2ff63cd759..323330dd359f95c1ae3d0c35bd6fcb8291a33a07 100644
> --- a/drivers/media/v4l2-core/Makefile
> +++ b/drivers/media/v4l2-core/Makefile
> @@ -11,7 +11,8 @@ tuner-objs	:=	tuner-core.o
>  videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \
>  			v4l2-event.o v4l2-subdev.o v4l2-common.o \
>  			v4l2-ctrls-core.o v4l2-ctrls-api.o \
> -			v4l2-ctrls-request.o v4l2-ctrls-defs.o
> +			v4l2-ctrls-request.o v4l2-ctrls-defs.o \
> +			v4l2-params.o
>  
>  # Please keep it alphabetically sorted by Kconfig name
>  # (e. g. LC_ALL=C sort Makefile)
> diff --git a/drivers/media/v4l2-core/v4l2-params.c b/drivers/media/v4l2-core/v4l2-params.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..8eeb12414c0981c13725a59d1668c5798b9fcf50
> --- /dev/null
> +++ b/drivers/media/v4l2-core/v4l2-params.c
> @@ -0,0 +1,123 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Video4Linux2 extensible parameters helpers
> + *
> + * Copyright (C) 2025 Ideas On Board Oy
> + * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> + */
> +
> +#include <media/v4l2-params.h>
> +
> +int v4l2_params_buffer_validate(struct device *dev, struct vb2_buffer *vb,
> +				size_t max_size,
> +				v4l2_params_validate_buffer buffer_validate)
> +{
> +	size_t header_size = offsetof(struct v4l2_params_buffer, data);
> +	struct v4l2_params_buffer *buffer = vb2_plane_vaddr(vb, 0);
> +	size_t payload_size = vb2_get_plane_payload(vb, 0);
> +	size_t buffer_size;
> +	int ret;
> +
> +	/* Payload size can't be greater than the destination buffer size */
> +	if (payload_size > max_size) {
> +		dev_dbg(dev, "Payload size is too large: %zu\n", payload_size);
> +		return -EINVAL;
> +	}
> +
> +	/* Payload size can't be smaller than the header size */
> +	if (payload_size < header_size) {
> +		dev_dbg(dev, "Payload size is too small: %zu\n", payload_size);
> +		return -EINVAL;
> +	}
> +
> +	/* Validate the size reported in the parameter buffer header */
> +	buffer_size = header_size + buffer->data_size;
> +	if (buffer_size != payload_size) {
> +		dev_dbg(dev, "Data size %zu and payload size %zu are different\n",
> +			buffer_size, payload_size);
> +		return -EINVAL;
> +	}
> +
> +	/* Driver-specific buffer validation. */
> +	if (buffer_validate) {
> +		ret = buffer_validate(dev, buffer);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_params_buffer_validate);
> +
> +int v4l2_params_blocks_validate(struct device *dev,
> +				const struct v4l2_params_buffer *buffer,
> +				const struct v4l2_params_handler *handlers,
> +				size_t num_handlers,
> +				v4l2_params_validate_block block_validate)
> +{
> +	size_t block_offset = 0;
> +	size_t buffer_size;
> +	int ret;
> +
> +	/* Walk the list of parameter blocks and validate them. */
> +	buffer_size = buffer->data_size;
> +	while (buffer_size >= sizeof(struct v4l2_params_block_header)) {
> +		const struct v4l2_params_handler *handler;
> +		const struct v4l2_params_block_header *block;
> +
> +		/* Validate block sizes and types against the handlers. */
> +		block = (const struct v4l2_params_block_header *)
> +			(buffer->data + block_offset);
> +
> +		if (block->type >= num_handlers) {
> +			dev_dbg(dev, "Invalid parameters block type\n");
> +			return -EINVAL;
> +		}
> +
> +		if (block->size > buffer_size) {
> +			dev_dbg(dev, "Premature end of parameters data\n");
> +			return -EINVAL;
> +		}
> +
> +		/* It's invalid to specify both ENABLE and DISABLE. */
> +		if ((block->flags & (V4L2_PARAMS_FL_BLOCK_ENABLE |
> +				     V4L2_PARAMS_FL_BLOCK_DISABLE)) ==
> +		     (V4L2_PARAMS_FL_BLOCK_ENABLE |
> +		     V4L2_PARAMS_FL_BLOCK_DISABLE)) {
> +			dev_dbg(dev, "Invalid parameters block flags\n");

There's also hweight*(); up to you.

> +			return -EINVAL;
> +		}
> +
> +		/*
> +		 * Match the block reported size against the handler's expected
> +		 * one, but allow the block to only contain the header in
> +		 * case it is going to be disabled.
> +		 */
> +		handler = &handlers[block->type];
> +		if (block->size != handler->size) {
> +			if (!(block->flags & V4L2_PARAMS_FL_BLOCK_DISABLE) ||
> +			      block->size != sizeof(*block)) {

You could merge the two conditions.

> +				dev_dbg(dev, "Invalid parameters block size\n");
> +				return -EINVAL;
> +			}
> +		}
> +
> +		/* Driver-specific per-block validation. */
> +		if (block_validate) {
> +			ret = block_validate(dev, block);
> +			if (ret)
> +				return ret;
> +		}
> +
> +		block_offset += block->size;
> +		buffer_size -= block->size;
> +	}
> +
> +	if (buffer_size) {
> +		dev_dbg(dev, "Unexpected data after the parameters buffer end\n");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_params_blocks_validate);
> diff --git a/include/media/v4l2-params.h b/include/media/v4l2-params.h
> new file mode 100644
> index 0000000000000000000000000000000000000000..a8a4cc721bc4a51d8a6f9c7c009b34dfa3579229
> --- /dev/null
> +++ b/include/media/v4l2-params.h
> @@ -0,0 +1,165 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Video4Linux2 extensible parameters helpers
> + *
> + * Copyright (C) 2025 Ideas On Board Oy
> + * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> + */
> +
> +#ifndef V4L2_PARAMS_H_
> +#define V4L2_PARAMS_H_
> +
> +#include <linux/media/v4l2-extensible-params.h>
> +
> +#include <linux/device.h>

Alphabetic order?

> +
> +#include <media/videobuf2-core.h>

Please use forward declarations instead of including the entire header
here.

> +
> +/**
> + * typedef v4l2_params_block_handler - V4L2 extensible format block handler
> + * @arg: pointer the driver-specific argument
> + * @block: the ISP configuration block to handle
> + *
> + * Defines the function signature of the functions that handle an ISP block
> + * configuration.
> + */
> +typedef void (*v4l2_params_block_handler)(void *arg,
> +					  const struct v4l2_params_block_header *block);
> +
> +/**
> + * struct v4l2_params_handler - V4L2 extensible format handler
> + * @size: the block expected size
> + * @handler: the block handler function
> + * @group: the device-specific group id the block belongs to (optional)
> + * @features: the device-specific features flags (optional)
> + *
> + * The v4l2_params_handler defines the type that driver making use of the
> + * V4L2 extensible parameters shall use to define their own ISP block
> + * handlers.
> + *
> + * Drivers shall prepare a list of handlers, one for each supported ISP block
> + * and correctly populate the structure's field with the expected block @size
> + * (used for validation), a pointer to each block @handler function and an
> + * optional @group and @feature flags, the driver can use to differentiate which
> + * ISP blocks are present on the ISP implementation.
> + *
> + * The @group field is intended to be used as a bitmask of driver-specific
> + * flags to allow the driver to setup certain blocks at different times. As an
> + * example an ISP driver can divide its block handlers in "pre-configure" blocks
> + * and "run-time" blocks and use the @group bitmask to identify the ISP blocks
> + * that have to be pre-configured from the ones that only have to be handled at
> + * run-time. The usage and definition of the @group field is totally
> + * driver-specific.
> + *
> + * The @features flag can instead be used to differentiate between blocks
> + * implemented in different revisions of the ISP design. In example some ISP
> + * blocks might be present on more recent revision than others. Populating the
> + * @features bitmask with the ISP/SoC machine identifier allows the driver to
> + * correctly ignore the blocks not supported on the ISP revision it is running
> + * on. As per the @group bitmask, the usage and definition of the @features
> + * field is totally driver-specific.
> + */
> +struct v4l2_params_handler {
> +	size_t size;
> +	v4l2_params_block_handler handler;
> +	unsigned int group;
> +	unsigned int features;
> +};
> +
> +/**
> + * typedef v4l2_params_validate_buffer - V4L2 extensible parameters buffer
> + *					 validation callback
> + * @dev: the driver's device pointer (as passed by the driver to
> + *	 v4l2_params_buffer_validate())
> + * @buffer: the extensible parameters buffer
> + *
> + * Defines the function prototype for the driver's callback to perform
> + * driver-specific validation on the extensible parameters buffer
> + */
> +typedef int (*v4l2_params_validate_buffer)(struct device *dev,
> +					   const struct v4l2_params_buffer *buffer);
> +
> +/**
> + * v4l2_params_buffer_validate - Validate a V4L2 extensible parameters buffer
> + * @dev: the driver's device pointer
> + * @vb: the videobuf2 buffer
> + * @max_size: the maximum allowed buffer size
> + * @buffer_validate: callback to the driver-specific buffer validation
> + *
> + * Helper function that performs validation of an extensible parameters buffer.
> + *
> + * The helper is meant to be used by drivers to perform validation of the
> + * extensible parameters buffer size correctness.
> + *
> + * The @vb buffer as received from the vb2 .buf_prepare() operation is checked
> + * against @max_size and its validated to be large enough to accommodate at
> + * least one ISP configuration block. The effective buffer size is compared
> + * with the reported data size to make sure they match.
> + *
> + * If provided, the @buffer_validate callback function is invoked to allow
> + * drivers to perform driver-specific validation (such as checking that the
> + * buffer version is supported).
> + *
> + * Drivers should use this function to validate the buffer size correctness
> + * before performing a copy of the user-provided videobuf2 buffer content into a
> + * kernel-only memory buffer to prevent userspace from modifying the buffer
> + * content after it has been submitted to the driver.
> + *.
> + * Examples of users of this function can be found in
> + * rkisp1_params_prepare_ext_params() and in c3_isp_params_vb2_buf_prepare().
> + */
> +int v4l2_params_buffer_validate(struct device *dev, struct vb2_buffer *vb,
> +				size_t max_size,
> +				v4l2_params_validate_buffer buffer_validate);
> +
> +/**
> + * typedef v4l2_params_validate_block - V4L2 extensible parameters block
> + *					validation callback
> + * @dev: the driver's device pointer (as passed by the driver to
> + *	 v4l2_params_validate())
> + * @block: the ISP configuration block to validate
> + *
> + * Defines the function prototype for the driver's callback to perform
> + * driver-specific validation on each ISP block.
> + */
> +typedef int (*v4l2_params_validate_block)(struct device *dev,
> +					  const struct v4l2_params_block_header *block);
> +
> +/**
> + * v4l2_params_blocks_validate - Validate V4L2 extensible parameters ISP
> + *				 configuration blocks
> + * @dev: the driver's device pointer
> + * @buffer: the extensible parameters configuration buffer
> + * @handlers: the list of block handlers
> + * @num_handlers: the number of block handlers
> + * @block_validate: callback to the driver-specific per-block validation
> + *		    function
> + *
> + * Helper function that performs validation of the ISP configuration blocks in
> + * an extensible parameters buffer.
> + *
> + * The helper is meant to be used by drivers to perform validation of the
> + * ISP configuration data blocks. For each block in the extensible parameters
> + * buffer, its size and correctness are validated against its associated handler
> + * in the @handlers list. Additionally, if provided, the @block_validate
> + * callback is invoked on each block to allow drivers to perform driver-specific
> + * validation.
> + *
> + * Drivers should use this function to validate the ISP configuration blocks
> + * after having validated the correctness of the vb2 buffer sizes by using the
> + * v4l2_params_buffer_validate() helper first. Once the buffer size has been
> + * validated, drivers should perform a copy of the user-provided buffer into a
> + * kernel-only memory buffer to prevent userspace from modifying the buffer
> + * content after it has been submitted to the driver, and then call this
> + * function to perform per-block validation.
> + *
> + * Examples of users of this function can be found in
> + * rkisp1_params_prepare_ext_params() and in c3_isp_params_vb2_buf_prepare().
> + */
> +int v4l2_params_blocks_validate(struct device *dev,
> +				const struct v4l2_params_buffer *buffer,
> +				const struct v4l2_params_handler *handlers,
> +				size_t num_handlers,
> +				v4l2_params_validate_block block_validate);
> +
> +#endif /* V4L2_PARAMS_H_ */
> 

-- 
Regards,

Sakari Ailus

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Re: [PATCH v3 5/8] media: v4l2-common: Introduce v4l2-params.c

[Jacopo Mondi]

Hi Sakari

On Wed, Aug 20, 2025 at 01:20:47AM +0300, Sakari Ailus wrote:
> Hi Jacopo,
>
> In the subject:
>
> s/common/params/

I actually meant "media: v4l2-core:"

>
> On Tue, Aug 19, 2025 at 04:54:46PM +0200, Jacopo Mondi wrote:
> > Add to the v4l2 framework an helper function to support drivers
> > when validating a buffer of extensible parameters.
> >
> > Introduce new types in include/media/v4l2-params.h that drivers shall
> > use in order to comply with the v4l2-params validation procedure, and
> > add a helper functions to v4l2-params.c to perform block and buffer
> > validation.
> >
> > Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
> > Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > ---
> >  MAINTAINERS                           |   2 +
> >  drivers/media/v4l2-core/Makefile      |   3 +-
> >  drivers/media/v4l2-core/v4l2-params.c | 123 +++++++++++++++++++++++++
> >  include/media/v4l2-params.h           | 165 ++++++++++++++++++++++++++++++++++
> >  4 files changed, 292 insertions(+), 1 deletion(-)
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 91df04e5d9022ccf2aea4445247369a8b86a4264..008f984c0769691f6ddec8d8f0f461fde056ddb3 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -26385,6 +26385,8 @@ M:	Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> >  L:	linux-media@vger.kernel.org
> >  S:	Maintained
> >  F:	Documentation/userspace-api/media/v4l/extensible-parameters.rst
> > +F:	drivers/media/v4l2-core/v4l2-params.c
> > +F:	include/media/v4l2-params.h
> >  F:	include/uapi/linux/media/v4l2-extensible-params.h
> >
> >  VF610 NAND DRIVER
> > diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
> > index 2177b9d63a8ffc1127c5a70118249a2ff63cd759..323330dd359f95c1ae3d0c35bd6fcb8291a33a07 100644
> > --- a/drivers/media/v4l2-core/Makefile
> > +++ b/drivers/media/v4l2-core/Makefile
> > @@ -11,7 +11,8 @@ tuner-objs	:=	tuner-core.o
> >  videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \
> >  			v4l2-event.o v4l2-subdev.o v4l2-common.o \
> >  			v4l2-ctrls-core.o v4l2-ctrls-api.o \
> > -			v4l2-ctrls-request.o v4l2-ctrls-defs.o
> > +			v4l2-ctrls-request.o v4l2-ctrls-defs.o \
> > +			v4l2-params.o
> >
> >  # Please keep it alphabetically sorted by Kconfig name
> >  # (e. g. LC_ALL=C sort Makefile)
> > diff --git a/drivers/media/v4l2-core/v4l2-params.c b/drivers/media/v4l2-core/v4l2-params.c
> > new file mode 100644
> > index 0000000000000000000000000000000000000000..8eeb12414c0981c13725a59d1668c5798b9fcf50
> > --- /dev/null
> > +++ b/drivers/media/v4l2-core/v4l2-params.c
> > @@ -0,0 +1,123 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * Video4Linux2 extensible parameters helpers
> > + *
> > + * Copyright (C) 2025 Ideas On Board Oy
> > + * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > + */
> > +
> > +#include <media/v4l2-params.h>
> > +
> > +int v4l2_params_buffer_validate(struct device *dev, struct vb2_buffer *vb,
> > +				size_t max_size,
> > +				v4l2_params_validate_buffer buffer_validate)
> > +{
> > +	size_t header_size = offsetof(struct v4l2_params_buffer, data);
> > +	struct v4l2_params_buffer *buffer = vb2_plane_vaddr(vb, 0);
> > +	size_t payload_size = vb2_get_plane_payload(vb, 0);
> > +	size_t buffer_size;
> > +	int ret;
> > +
> > +	/* Payload size can't be greater than the destination buffer size */
> > +	if (payload_size > max_size) {
> > +		dev_dbg(dev, "Payload size is too large: %zu\n", payload_size);
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* Payload size can't be smaller than the header size */
> > +	if (payload_size < header_size) {
> > +		dev_dbg(dev, "Payload size is too small: %zu\n", payload_size);
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* Validate the size reported in the parameter buffer header */
> > +	buffer_size = header_size + buffer->data_size;
> > +	if (buffer_size != payload_size) {
> > +		dev_dbg(dev, "Data size %zu and payload size %zu are different\n",
> > +			buffer_size, payload_size);
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* Driver-specific buffer validation. */
> > +	if (buffer_validate) {
> > +		ret = buffer_validate(dev, buffer);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(v4l2_params_buffer_validate);
> > +
> > +int v4l2_params_blocks_validate(struct device *dev,
> > +				const struct v4l2_params_buffer *buffer,
> > +				const struct v4l2_params_handler *handlers,
> > +				size_t num_handlers,
> > +				v4l2_params_validate_block block_validate)
> > +{
> > +	size_t block_offset = 0;
> > +	size_t buffer_size;
> > +	int ret;
> > +
> > +	/* Walk the list of parameter blocks and validate them. */
> > +	buffer_size = buffer->data_size;
> > +	while (buffer_size >= sizeof(struct v4l2_params_block_header)) {
> > +		const struct v4l2_params_handler *handler;
> > +		const struct v4l2_params_block_header *block;
> > +
> > +		/* Validate block sizes and types against the handlers. */
> > +		block = (const struct v4l2_params_block_header *)
> > +			(buffer->data + block_offset);
> > +
> > +		if (block->type >= num_handlers) {
> > +			dev_dbg(dev, "Invalid parameters block type\n");
> > +			return -EINVAL;
> > +		}
> > +
> > +		if (block->size > buffer_size) {
> > +			dev_dbg(dev, "Premature end of parameters data\n");
> > +			return -EINVAL;
> > +		}
> > +
> > +		/* It's invalid to specify both ENABLE and DISABLE. */
> > +		if ((block->flags & (V4L2_PARAMS_FL_BLOCK_ENABLE |
> > +				     V4L2_PARAMS_FL_BLOCK_DISABLE)) ==
> > +		     (V4L2_PARAMS_FL_BLOCK_ENABLE |
> > +		     V4L2_PARAMS_FL_BLOCK_DISABLE)) {
> > +			dev_dbg(dev, "Invalid parameters block flags\n");
>
> There's also hweight*(); up to you.
>

Better, yes

> > +			return -EINVAL;
> > +		}
> > +
> > +		/*
> > +		 * Match the block reported size against the handler's expected
> > +		 * one, but allow the block to only contain the header in
> > +		 * case it is going to be disabled.
> > +		 */
> > +		handler = &handlers[block->type];
> > +		if (block->size != handler->size) {
> > +			if (!(block->flags & V4L2_PARAMS_FL_BLOCK_DISABLE) ||
> > +			      block->size != sizeof(*block)) {
>
> You could merge the two conditions.
>

Indeed

> > +				dev_dbg(dev, "Invalid parameters block size\n");
> > +				return -EINVAL;
> > +			}
> > +		}
> > +
> > +		/* Driver-specific per-block validation. */
> > +		if (block_validate) {
> > +			ret = block_validate(dev, block);
> > +			if (ret)
> > +				return ret;
> > +		}
> > +
> > +		block_offset += block->size;
> > +		buffer_size -= block->size;
> > +	}
> > +
> > +	if (buffer_size) {
> > +		dev_dbg(dev, "Unexpected data after the parameters buffer end\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(v4l2_params_blocks_validate);
> > diff --git a/include/media/v4l2-params.h b/include/media/v4l2-params.h
> > new file mode 100644
> > index 0000000000000000000000000000000000000000..a8a4cc721bc4a51d8a6f9c7c009b34dfa3579229
> > --- /dev/null
> > +++ b/include/media/v4l2-params.h
> > @@ -0,0 +1,165 @@
> > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > +/*
> > + * Video4Linux2 extensible parameters helpers
> > + *
> > + * Copyright (C) 2025 Ideas On Board Oy
> > + * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > + */
> > +
> > +#ifndef V4L2_PARAMS_H_
> > +#define V4L2_PARAMS_H_
> > +
> > +#include <linux/media/v4l2-extensible-params.h>
> > +
> > +#include <linux/device.h>
>
> Alphabetic order?
>

I thought the rule was to include the header that corresponds to the
.c file first to make sure it's self-contained...

> > +
> > +#include <media/videobuf2-core.h>
>
> Please use forward declarations instead of including the entire header
> here.
>

Good idea

Thanks
  j

> > +
> > +/**
> > + * typedef v4l2_params_block_handler - V4L2 extensible format block handler
> > + * @arg: pointer the driver-specific argument
> > + * @block: the ISP configuration block to handle
> > + *
> > + * Defines the function signature of the functions that handle an ISP block
> > + * configuration.
> > + */
> > +typedef void (*v4l2_params_block_handler)(void *arg,
> > +					  const struct v4l2_params_block_header *block);
> > +
> > +/**
> > + * struct v4l2_params_handler - V4L2 extensible format handler
> > + * @size: the block expected size
> > + * @handler: the block handler function
> > + * @group: the device-specific group id the block belongs to (optional)
> > + * @features: the device-specific features flags (optional)
> > + *
> > + * The v4l2_params_handler defines the type that driver making use of the
> > + * V4L2 extensible parameters shall use to define their own ISP block
> > + * handlers.
> > + *
> > + * Drivers shall prepare a list of handlers, one for each supported ISP block
> > + * and correctly populate the structure's field with the expected block @size
> > + * (used for validation), a pointer to each block @handler function and an
> > + * optional @group and @feature flags, the driver can use to differentiate which
> > + * ISP blocks are present on the ISP implementation.
> > + *
> > + * The @group field is intended to be used as a bitmask of driver-specific
> > + * flags to allow the driver to setup certain blocks at different times. As an
> > + * example an ISP driver can divide its block handlers in "pre-configure" blocks
> > + * and "run-time" blocks and use the @group bitmask to identify the ISP blocks
> > + * that have to be pre-configured from the ones that only have to be handled at
> > + * run-time. The usage and definition of the @group field is totally
> > + * driver-specific.
> > + *
> > + * The @features flag can instead be used to differentiate between blocks
> > + * implemented in different revisions of the ISP design. In example some ISP
> > + * blocks might be present on more recent revision than others. Populating the
> > + * @features bitmask with the ISP/SoC machine identifier allows the driver to
> > + * correctly ignore the blocks not supported on the ISP revision it is running
> > + * on. As per the @group bitmask, the usage and definition of the @features
> > + * field is totally driver-specific.
> > + */
> > +struct v4l2_params_handler {
> > +	size_t size;
> > +	v4l2_params_block_handler handler;
> > +	unsigned int group;
> > +	unsigned int features;
> > +};
> > +
> > +/**
> > + * typedef v4l2_params_validate_buffer - V4L2 extensible parameters buffer
> > + *					 validation callback
> > + * @dev: the driver's device pointer (as passed by the driver to
> > + *	 v4l2_params_buffer_validate())
> > + * @buffer: the extensible parameters buffer
> > + *
> > + * Defines the function prototype for the driver's callback to perform
> > + * driver-specific validation on the extensible parameters buffer
> > + */
> > +typedef int (*v4l2_params_validate_buffer)(struct device *dev,
> > +					   const struct v4l2_params_buffer *buffer);
> > +
> > +/**
> > + * v4l2_params_buffer_validate - Validate a V4L2 extensible parameters buffer
> > + * @dev: the driver's device pointer
> > + * @vb: the videobuf2 buffer
> > + * @max_size: the maximum allowed buffer size
> > + * @buffer_validate: callback to the driver-specific buffer validation
> > + *
> > + * Helper function that performs validation of an extensible parameters buffer.
> > + *
> > + * The helper is meant to be used by drivers to perform validation of the
> > + * extensible parameters buffer size correctness.
> > + *
> > + * The @vb buffer as received from the vb2 .buf_prepare() operation is checked
> > + * against @max_size and its validated to be large enough to accommodate at
> > + * least one ISP configuration block. The effective buffer size is compared
> > + * with the reported data size to make sure they match.
> > + *
> > + * If provided, the @buffer_validate callback function is invoked to allow
> > + * drivers to perform driver-specific validation (such as checking that the
> > + * buffer version is supported).
> > + *
> > + * Drivers should use this function to validate the buffer size correctness
> > + * before performing a copy of the user-provided videobuf2 buffer content into a
> > + * kernel-only memory buffer to prevent userspace from modifying the buffer
> > + * content after it has been submitted to the driver.
> > + *.
> > + * Examples of users of this function can be found in
> > + * rkisp1_params_prepare_ext_params() and in c3_isp_params_vb2_buf_prepare().
> > + */
> > +int v4l2_params_buffer_validate(struct device *dev, struct vb2_buffer *vb,
> > +				size_t max_size,
> > +				v4l2_params_validate_buffer buffer_validate);
> > +
> > +/**
> > + * typedef v4l2_params_validate_block - V4L2 extensible parameters block
> > + *					validation callback
> > + * @dev: the driver's device pointer (as passed by the driver to
> > + *	 v4l2_params_validate())
> > + * @block: the ISP configuration block to validate
> > + *
> > + * Defines the function prototype for the driver's callback to perform
> > + * driver-specific validation on each ISP block.
> > + */
> > +typedef int (*v4l2_params_validate_block)(struct device *dev,
> > +					  const struct v4l2_params_block_header *block);
> > +
> > +/**
> > + * v4l2_params_blocks_validate - Validate V4L2 extensible parameters ISP
> > + *				 configuration blocks
> > + * @dev: the driver's device pointer
> > + * @buffer: the extensible parameters configuration buffer
> > + * @handlers: the list of block handlers
> > + * @num_handlers: the number of block handlers
> > + * @block_validate: callback to the driver-specific per-block validation
> > + *		    function
> > + *
> > + * Helper function that performs validation of the ISP configuration blocks in
> > + * an extensible parameters buffer.
> > + *
> > + * The helper is meant to be used by drivers to perform validation of the
> > + * ISP configuration data blocks. For each block in the extensible parameters
> > + * buffer, its size and correctness are validated against its associated handler
> > + * in the @handlers list. Additionally, if provided, the @block_validate
> > + * callback is invoked on each block to allow drivers to perform driver-specific
> > + * validation.
> > + *
> > + * Drivers should use this function to validate the ISP configuration blocks
> > + * after having validated the correctness of the vb2 buffer sizes by using the
> > + * v4l2_params_buffer_validate() helper first. Once the buffer size has been
> > + * validated, drivers should perform a copy of the user-provided buffer into a
> > + * kernel-only memory buffer to prevent userspace from modifying the buffer
> > + * content after it has been submitted to the driver, and then call this
> > + * function to perform per-block validation.
> > + *
> > + * Examples of users of this function can be found in
> > + * rkisp1_params_prepare_ext_params() and in c3_isp_params_vb2_buf_prepare().
> > + */
> > +int v4l2_params_blocks_validate(struct device *dev,
> > +				const struct v4l2_params_buffer *buffer,
> > +				const struct v4l2_params_handler *handlers,
> > +				size_t num_handlers,
> > +				v4l2_params_validate_block block_validate);
> > +
> > +#endif /* V4L2_PARAMS_H_ */
> >
>
> --
> Regards,
>
> Sakari Ailus

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Re: [PATCH v3 1/8] media: uapi: Introduce V4L2 extensible params

[Jacopo Mondi]

Hi Sakari

On Wed, Aug 20, 2025 at 01:07:58AM +0300, Sakari Ailus wrote:
> Hi Jacopo,
>
> Thank you for working on this.
>

Thanks for the quick review

> On Tue, Aug 19, 2025 at 04:54:42PM +0200, Jacopo Mondi wrote:
> > Introduce v4l2-extensible-params.h in the Linux kernel uAPI.
> >
> > The header defines two types that all drivers that use the extensible
> > parameters format for ISP configuration shall use to build their own
> > format versions.
> >
> > The newly introduce type v4l2_params_block represent the
> > header to be prepend to each ISP configuration block and the
> > v4l2_params_buffer type represent the base type for the configuration
> > parameters buffer.
> >
> > The v4l2_params_buffer represents the container for the ISP
> > configuration data block. The generic type is defined with a 0-sized
> > data block that specific ISP implementation shall properly size
> > according to their capabilities.
> >
> > [Add v4l2_params_buffer_size()]
> >
> > Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
> > Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
> > Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > ---
> >  MAINTAINERS                                       |   6 +
> >  include/uapi/linux/media/v4l2-extensible-params.h | 144 ++++++++++++++++++++++
> >  2 files changed, 150 insertions(+)
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index fe168477caa45799dfe07de2f54de6d6a1ce0615..67216d1e92d7ac81617bb3c4329e4096aa205706 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -26380,6 +26380,12 @@ F:	drivers/media/i2c/vd55g1.c
> >  F:	drivers/media/i2c/vd56g3.c
> >  F:	drivers/media/i2c/vgxy61.c
> >
> > +V4L2 EXTENSIBLE PARAMETERS FORMAT
> > +M:	Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > +L:	linux-media@vger.kernel.org
> > +S:	Maintained
> > +F:	include/uapi/linux/media/v4l2-extensible-params.h
> > +
> >  VF610 NAND DRIVER
> >  M:	Stefan Agner <stefan@agner.ch>
> >  L:	linux-mtd@lists.infradead.org
> > diff --git a/include/uapi/linux/media/v4l2-extensible-params.h b/include/uapi/linux/media/v4l2-extensible-params.h
> > new file mode 100644
> > index 0000000000000000000000000000000000000000..ace89299a4b37e428c0bc9a72fbc079b1dcda91a
> > --- /dev/null
> > +++ b/include/uapi/linux/media/v4l2-extensible-params.h
> > @@ -0,0 +1,144 @@
> > +/* SPDX-License-Identifier: ((GPL-2.0+ WITH Linux-syscall-note) OR MIT) */
> > +/*
> > + * Video4Linux2 extensible configuration parameters base types
> > + *
> > + * Copyright (C) 2025 Ideas On Board Oy
> > + * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > + */
> > +
> > +#ifndef _UAPI_V4L2_PARAMS_H_
> > +#define _UAPI_V4L2_PARAMS_H_
> > +
> > +#include <linux/types.h>
> > +
> > +#define V4L2_PARAMS_FL_BLOCK_DISABLE	(1U << 0)
> > +#define V4L2_PARAMS_FL_BLOCK_ENABLE	(1U << 1)
> > +
> > +/*
> > + * Reserve the first 8 bits for V4L2_PARAMS_FL_* flag. Platform-specific flags
> > + * should be defined as:
> > + * #define PLATFORM_SPECIFIC_FLAG0	((1U << V4L2_PARAMS_FL_PLATFORM_FLAGS(0))
> > + * #define PLATFORM_SPECIFIC_FLAG1	((1U << V4L2_PARAMS_FL_PLATFORM_FLAGS(1))
>
> How many bits are you shifting left here again?

More than what I wanted to

The shift in V4L2_PARAMS_FL_PLATFORM_FLAGS is a leftover from a
previous version, sorry about that

>
> > + */
> > +#define V4L2_PARAMS_FL_PLATFORM_FLAGS(n)	((n) << 8)
>
> n really needs to be unsigned.

Any idea how to guarantee that ?

I think I will:

#define V4L2_PARAMS_FL_PLATFORM_FLAGS(n)	((n) + 8)

So that users can:

 * #define PLATFORM_SPECIFIC_FLAG0	((1U << V4L2_PARAMS_FL_PLATFORM_FLAGS(0))
 * #define PLATFORM_SPECIFIC_FLAG1	((1U << V4L2_PARAMS_FL_PLATFORM_FLAGS(1))

>
> > +
> > +/**
> > + * struct v4l2_params_block_header - V4L2 extensible parameters block header
> > + *
> > + * This structure represents the common part of all the ISP configuration
> > + * blocks. Each parameters block shall embed an instance of this structure type
> > + * as its first member, followed by the block-specific configuration data. The
> > + * driver inspects this common header to discern the block type and its size and
> > + * properly handle the block content by casting it to the correct block-specific
> > + * type.
> > + *
> > + * The @type field is one of the values enumerated by each platform-specific ISP
> > + * block types which specifies how the data should be interpreted by the driver.
> > + * The @size field specifies the size of the parameters block and is used by the
> > + * driver for validation purposes.
> > + *
> > + * The @flags field is a bitmask of per-block flags V4L2_PARAMS_FL_* and
> > + * platform-specific flags specified by the platform-specific header.
> > + *
> > + * Documentation of the platform-specific flags handling is specified by the
> > + * platform-specific block header type:
> > + *
> > + * - Rockchip RkISP1: :c:type:`rkisp1_ext_params_block_type`
> > + * - Amlogic C3: :c:type:`c3_isp_params_block_type`
> > + *
> > + * Userspace is responsible for correctly populating the parameters block header
> > + * fields (@type, @flags and @size) and the block-specific parameters.
> > + *
> > + * @type: The parameters block type (platform-specific)
> > + * @flags: A bitmask of block flags (platform-specific)
> > + * @size: Size (in bytes) of the parameters block, including this header
> > + */
> > +struct v4l2_params_block_header {
> > +	__u16 type;
> > +	__u16 flags;
> > +	__u32 size;
> > +} __attribute__((aligned(8)));
> > +
> > +/**
> > + * v4l2_params_buffer_size - Calculate size of v4l2_params_buffer for a platform
> > + *
> > + * Users of the v4l2 extensible parameters will have differing sized data arrays
> > + * depending on their specific parameter buffers. Drivers and userspace will
> > + * need to be able to calculate the appropriate size of the struct to
> > + * accommodate all ISP configuration blocks provided by the platform.
> > + * This macro provides a convenient tool for the calculation.
> > + *
> > + * Each driver shall provide a definition of their extensible parameters
> > + * implementation data buffer size. As an example:
> > + *
> > + * #define PLATFORM_BLOCKS_MAX_SIZE		\
> > + *	sizeof(platform_block_0)	+	\
> > + *	sizeof(platform_block_1)
> > + *
> > + * #define PLATFORM_BUFFER_SIZE			\
> > + *	v4l2_params_buffer_size(PLATFORM_BLOCKS_MAX_SIZE)
> > + *
> > + * Drivers are then responsible for allocating buffers of the proper size
> > + * by assigning PLATFORM_BUFFER_SIZE to the per-plane size of the videobuf2
> > + * .queue_setup() operation and userspace shall use PLATFORM_BUFFER_SIZE
> > + * when populating the ISP configuration data buffer.
> > + *
> > + * @max_params_size: The total size of the ISP configuration blocks
> > + */
> > +#define v4l2_params_buffer_size(max_params_size) \
> > +	(offsetof(struct v4l2_params_buffer, data) + (max_params_size))
> > +
> > +/**
> > + * struct v4l2_params_buffer - V4L2 extensible parameters configuration
> > + *
> > + * This struct contains the configuration parameters of the ISP algorithms,
> > + * serialized by userspace into a data buffer. Each configuration parameter
> > + * block is represented by a block-specific structure which contains a
> > + * :c:type:`v4l2_params_block_header` entry as first member. Userspace populates
> > + * the @data buffer with configuration parameters for the blocks that it intends
> > + * to configure. As a consequence, the data buffer effective size changes
> > + * according to the number of ISP blocks that userspace intends to configure and
> > + * is set by userspace in the @data_size field.
> > + *
> > + * The parameters buffer is versioned by the @version field to allow modifying
> > + * and extending its definition. Userspace shall populate the @version field to
> > + * inform the driver about the version it intends to use. The driver will parse
> > + * and handle the @data buffer according to the data layout specific to the
> > + * indicated version and return an error if the desired version is not
> > + * supported.
> > + *
> > + * For each ISP block that userspace wants to configure, a block-specific
> > + * structure is appended to the @data buffer, one after the other without gaps
> > + * in between nor overlaps. Userspace shall populate the @data_size field with
> > + * the effective size, in bytes, of the @data buffer.
> > + *
> > + * Drivers shall take care of properly sizing of the extensible parameters
> > + * buffer @data array. The v4l2_params_buffer type is defined with a
> > + * flexible-array-member at the end, which resolves to a size of 0 bytes when
> > + * inspected with sizeof(struct v4l2_params_buffer). This of course is not
> > + * suitable for neither buffer allocation in the kernel driver nor for proper
> > + * handling in userspace of the @data buffer it has to populate.
> > + *
> > + * Drivers using this type in their userspace API definition are responsible
> > + * for providing the exact definition of the @data buffer size using the
> > + * v4l2_params_buffer_size() macro. The size shall be used
> > + * by the driver for buffers allocation and by userspace for populating the
> > + * @data buffer before queueing it to the driver
> > + *
> > + * Drivers that were already using extensible-parameters before the introduction
> > + * of this file define their own type-convertible implementation of this
> > + * type, see:
> > + * - Rockchip RkISP1: :c:type:`rkisp1_ext_params_cfg`
> > + * - Amlogic C3: :c:type:`c3_isp_params_cfg`
> > + *
> > + * @version: The parameters buffer version (platform-specific)
> > + * @data_size: The configuration data effective size, excluding this header
> > + * @data: The configuration data
> > + */
> > +struct v4l2_params_buffer {
> > +	__u32 version;
> > +	__u32 data_size;
> > +	__u8 data[];
>
> Would __attribute__((__counted_by__(data_size))) be problematic here?

Nice, didn't know about that. Read a bit through [1] and [2] and
there's one thing that it is not clear to me:

From [2]:

* 'p->array' has _at least_ 'p->count' number of elements
  available all the time.  This relationship must hold even
  after any of these related objects are updated during the
  program.

I wonder what "number of elements available all the time" means. It is
simply about the fact that the allocated space that follows the
flexible array member should be larger that the p->count value ?

I played a bit with __counted__by() and it seems to be the the case.

[1] https://embeddedor.com/blog/2024/06/18/how-to-use-the-new-counted_by-attribute-in-c-and-linux/
[2] https://gcc.gnu.org/pipermail/gcc-patches/2024-May/653123.html
>
> Perhaps not now but it could be added later on?

I do expect applications in user-space that populates an extensible
parameters buffer to:

1) Operate on a large-enough data[] as the driver allocates the buffer
on their behalf using the per-platform MAX_SIZE (see
RKISP1_EXT_PARAMS_MAX_SIZE in example)

2) Populate the data[] array one block at the time. They can update
data_size easily before accessing data[]

So I presume we could as well add it right away ?

>
> > +};
> > +
> > +#endif /* _UAPI_V4L2_PARAMS_H_ */
> >
>
> --
> Kind regards,
>
> Sakari Ailus

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Re: [PATCH v3 5/8] media: v4l2-common: Introduce v4l2-params.c

[Jacopo Mondi]

Hi Sakari

On Wed, Aug 20, 2025 at 01:20:47AM +0300, Sakari Ailus wrote:
> Hi Jacopo,
>
> In the subject:
>
> s/common/params/
>
> On Tue, Aug 19, 2025 at 04:54:46PM +0200, Jacopo Mondi wrote:
> > Add to the v4l2 framework an helper function to support drivers
> > when validating a buffer of extensible parameters.
> >
> > Introduce new types in include/media/v4l2-params.h that drivers shall
> > use in order to comply with the v4l2-params validation procedure, and
> > add a helper functions to v4l2-params.c to perform block and buffer
> > validation.
> >
> > Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
> > Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > ---
> >  MAINTAINERS                           |   2 +
> >  drivers/media/v4l2-core/Makefile      |   3 +-
> >  drivers/media/v4l2-core/v4l2-params.c | 123 +++++++++++++++++++++++++
> >  include/media/v4l2-params.h           | 165 ++++++++++++++++++++++++++++++++++
> >  4 files changed, 292 insertions(+), 1 deletion(-)
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 91df04e5d9022ccf2aea4445247369a8b86a4264..008f984c0769691f6ddec8d8f0f461fde056ddb3 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -26385,6 +26385,8 @@ M:	Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> >  L:	linux-media@vger.kernel.org
> >  S:	Maintained
> >  F:	Documentation/userspace-api/media/v4l/extensible-parameters.rst
> > +F:	drivers/media/v4l2-core/v4l2-params.c
> > +F:	include/media/v4l2-params.h
> >  F:	include/uapi/linux/media/v4l2-extensible-params.h
> >
> >  VF610 NAND DRIVER
> > diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
> > index 2177b9d63a8ffc1127c5a70118249a2ff63cd759..323330dd359f95c1ae3d0c35bd6fcb8291a33a07 100644
> > --- a/drivers/media/v4l2-core/Makefile
> > +++ b/drivers/media/v4l2-core/Makefile
> > @@ -11,7 +11,8 @@ tuner-objs	:=	tuner-core.o
> >  videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \
> >  			v4l2-event.o v4l2-subdev.o v4l2-common.o \
> >  			v4l2-ctrls-core.o v4l2-ctrls-api.o \
> > -			v4l2-ctrls-request.o v4l2-ctrls-defs.o
> > +			v4l2-ctrls-request.o v4l2-ctrls-defs.o \
> > +			v4l2-params.o
> >
> >  # Please keep it alphabetically sorted by Kconfig name
> >  # (e. g. LC_ALL=C sort Makefile)
> > diff --git a/drivers/media/v4l2-core/v4l2-params.c b/drivers/media/v4l2-core/v4l2-params.c
> > new file mode 100644
> > index 0000000000000000000000000000000000000000..8eeb12414c0981c13725a59d1668c5798b9fcf50
> > --- /dev/null
> > +++ b/drivers/media/v4l2-core/v4l2-params.c
> > @@ -0,0 +1,123 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * Video4Linux2 extensible parameters helpers
> > + *
> > + * Copyright (C) 2025 Ideas On Board Oy
> > + * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > + */
> > +
> > +#include <media/v4l2-params.h>
> > +
> > +int v4l2_params_buffer_validate(struct device *dev, struct vb2_buffer *vb,
> > +				size_t max_size,
> > +				v4l2_params_validate_buffer buffer_validate)
> > +{
> > +	size_t header_size = offsetof(struct v4l2_params_buffer, data);
> > +	struct v4l2_params_buffer *buffer = vb2_plane_vaddr(vb, 0);
> > +	size_t payload_size = vb2_get_plane_payload(vb, 0);
> > +	size_t buffer_size;
> > +	int ret;
> > +
> > +	/* Payload size can't be greater than the destination buffer size */
> > +	if (payload_size > max_size) {
> > +		dev_dbg(dev, "Payload size is too large: %zu\n", payload_size);
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* Payload size can't be smaller than the header size */
> > +	if (payload_size < header_size) {
> > +		dev_dbg(dev, "Payload size is too small: %zu\n", payload_size);
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* Validate the size reported in the parameter buffer header */
> > +	buffer_size = header_size + buffer->data_size;
> > +	if (buffer_size != payload_size) {
> > +		dev_dbg(dev, "Data size %zu and payload size %zu are different\n",
> > +			buffer_size, payload_size);
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* Driver-specific buffer validation. */
> > +	if (buffer_validate) {
> > +		ret = buffer_validate(dev, buffer);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(v4l2_params_buffer_validate);
> > +
> > +int v4l2_params_blocks_validate(struct device *dev,
> > +				const struct v4l2_params_buffer *buffer,
> > +				const struct v4l2_params_handler *handlers,
> > +				size_t num_handlers,
> > +				v4l2_params_validate_block block_validate)
> > +{
> > +	size_t block_offset = 0;
> > +	size_t buffer_size;
> > +	int ret;
> > +
> > +	/* Walk the list of parameter blocks and validate them. */
> > +	buffer_size = buffer->data_size;
> > +	while (buffer_size >= sizeof(struct v4l2_params_block_header)) {
> > +		const struct v4l2_params_handler *handler;
> > +		const struct v4l2_params_block_header *block;
> > +
> > +		/* Validate block sizes and types against the handlers. */
> > +		block = (const struct v4l2_params_block_header *)
> > +			(buffer->data + block_offset);
> > +
> > +		if (block->type >= num_handlers) {
> > +			dev_dbg(dev, "Invalid parameters block type\n");
> > +			return -EINVAL;
> > +		}
> > +
> > +		if (block->size > buffer_size) {
> > +			dev_dbg(dev, "Premature end of parameters data\n");
> > +			return -EINVAL;
> > +		}
> > +
> > +		/* It's invalid to specify both ENABLE and DISABLE. */
> > +		if ((block->flags & (V4L2_PARAMS_FL_BLOCK_ENABLE |
> > +				     V4L2_PARAMS_FL_BLOCK_DISABLE)) ==
> > +		     (V4L2_PARAMS_FL_BLOCK_ENABLE |
> > +		     V4L2_PARAMS_FL_BLOCK_DISABLE)) {
> > +			dev_dbg(dev, "Invalid parameters block flags\n");
>
> There's also hweight*(); up to you.
>

I ended up leaving it the way it is.

ENABLE/DISABLE are mutally exclusive, while other flags might be not.

Let's wait to see what other flags we'll need

Thanks
   j

> > +			return -EINVAL;
> > +		}
> > +
> > +		/*
> > +		 * Match the block reported size against the handler's expected
> > +		 * one, but allow the block to only contain the header in
> > +		 * case it is going to be disabled.
> > +		 */
> > +		handler = &handlers[block->type];
> > +		if (block->size != handler->size) {
> > +			if (!(block->flags & V4L2_PARAMS_FL_BLOCK_DISABLE) ||
> > +			      block->size != sizeof(*block)) {
>
> You could merge the two conditions.
>
> > +				dev_dbg(dev, "Invalid parameters block size\n");
> > +				return -EINVAL;
> > +			}
> > +		}
> > +
> > +		/* Driver-specific per-block validation. */
> > +		if (block_validate) {
> > +			ret = block_validate(dev, block);
> > +			if (ret)
> > +				return ret;
> > +		}
> > +
> > +		block_offset += block->size;
> > +		buffer_size -= block->size;
> > +	}
> > +
> > +	if (buffer_size) {
> > +		dev_dbg(dev, "Unexpected data after the parameters buffer end\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(v4l2_params_blocks_validate);
> > diff --git a/include/media/v4l2-params.h b/include/media/v4l2-params.h
> > new file mode 100644
> > index 0000000000000000000000000000000000000000..a8a4cc721bc4a51d8a6f9c7c009b34dfa3579229
> > --- /dev/null
> > +++ b/include/media/v4l2-params.h
> > @@ -0,0 +1,165 @@
> > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > +/*
> > + * Video4Linux2 extensible parameters helpers
> > + *
> > + * Copyright (C) 2025 Ideas On Board Oy
> > + * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > + */
> > +
> > +#ifndef V4L2_PARAMS_H_
> > +#define V4L2_PARAMS_H_
> > +
> > +#include <linux/media/v4l2-extensible-params.h>
> > +
> > +#include <linux/device.h>
>
> Alphabetic order?
>
> > +
> > +#include <media/videobuf2-core.h>
>
> Please use forward declarations instead of including the entire header
> here.
>
> > +
> > +/**
> > + * typedef v4l2_params_block_handler - V4L2 extensible format block handler
> > + * @arg: pointer the driver-specific argument
> > + * @block: the ISP configuration block to handle
> > + *
> > + * Defines the function signature of the functions that handle an ISP block
> > + * configuration.
> > + */
> > +typedef void (*v4l2_params_block_handler)(void *arg,
> > +					  const struct v4l2_params_block_header *block);
> > +
> > +/**
> > + * struct v4l2_params_handler - V4L2 extensible format handler
> > + * @size: the block expected size
> > + * @handler: the block handler function
> > + * @group: the device-specific group id the block belongs to (optional)
> > + * @features: the device-specific features flags (optional)
> > + *
> > + * The v4l2_params_handler defines the type that driver making use of the
> > + * V4L2 extensible parameters shall use to define their own ISP block
> > + * handlers.
> > + *
> > + * Drivers shall prepare a list of handlers, one for each supported ISP block
> > + * and correctly populate the structure's field with the expected block @size
> > + * (used for validation), a pointer to each block @handler function and an
> > + * optional @group and @feature flags, the driver can use to differentiate which
> > + * ISP blocks are present on the ISP implementation.
> > + *
> > + * The @group field is intended to be used as a bitmask of driver-specific
> > + * flags to allow the driver to setup certain blocks at different times. As an
> > + * example an ISP driver can divide its block handlers in "pre-configure" blocks
> > + * and "run-time" blocks and use the @group bitmask to identify the ISP blocks
> > + * that have to be pre-configured from the ones that only have to be handled at
> > + * run-time. The usage and definition of the @group field is totally
> > + * driver-specific.
> > + *
> > + * The @features flag can instead be used to differentiate between blocks
> > + * implemented in different revisions of the ISP design. In example some ISP
> > + * blocks might be present on more recent revision than others. Populating the
> > + * @features bitmask with the ISP/SoC machine identifier allows the driver to
> > + * correctly ignore the blocks not supported on the ISP revision it is running
> > + * on. As per the @group bitmask, the usage and definition of the @features
> > + * field is totally driver-specific.
> > + */
> > +struct v4l2_params_handler {
> > +	size_t size;
> > +	v4l2_params_block_handler handler;
> > +	unsigned int group;
> > +	unsigned int features;
> > +};
> > +
> > +/**
> > + * typedef v4l2_params_validate_buffer - V4L2 extensible parameters buffer
> > + *					 validation callback
> > + * @dev: the driver's device pointer (as passed by the driver to
> > + *	 v4l2_params_buffer_validate())
> > + * @buffer: the extensible parameters buffer
> > + *
> > + * Defines the function prototype for the driver's callback to perform
> > + * driver-specific validation on the extensible parameters buffer
> > + */
> > +typedef int (*v4l2_params_validate_buffer)(struct device *dev,
> > +					   const struct v4l2_params_buffer *buffer);
> > +
> > +/**
> > + * v4l2_params_buffer_validate - Validate a V4L2 extensible parameters buffer
> > + * @dev: the driver's device pointer
> > + * @vb: the videobuf2 buffer
> > + * @max_size: the maximum allowed buffer size
> > + * @buffer_validate: callback to the driver-specific buffer validation
> > + *
> > + * Helper function that performs validation of an extensible parameters buffer.
> > + *
> > + * The helper is meant to be used by drivers to perform validation of the
> > + * extensible parameters buffer size correctness.
> > + *
> > + * The @vb buffer as received from the vb2 .buf_prepare() operation is checked
> > + * against @max_size and its validated to be large enough to accommodate at
> > + * least one ISP configuration block. The effective buffer size is compared
> > + * with the reported data size to make sure they match.
> > + *
> > + * If provided, the @buffer_validate callback function is invoked to allow
> > + * drivers to perform driver-specific validation (such as checking that the
> > + * buffer version is supported).
> > + *
> > + * Drivers should use this function to validate the buffer size correctness
> > + * before performing a copy of the user-provided videobuf2 buffer content into a
> > + * kernel-only memory buffer to prevent userspace from modifying the buffer
> > + * content after it has been submitted to the driver.
> > + *.
> > + * Examples of users of this function can be found in
> > + * rkisp1_params_prepare_ext_params() and in c3_isp_params_vb2_buf_prepare().
> > + */
> > +int v4l2_params_buffer_validate(struct device *dev, struct vb2_buffer *vb,
> > +				size_t max_size,
> > +				v4l2_params_validate_buffer buffer_validate);
> > +
> > +/**
> > + * typedef v4l2_params_validate_block - V4L2 extensible parameters block
> > + *					validation callback
> > + * @dev: the driver's device pointer (as passed by the driver to
> > + *	 v4l2_params_validate())
> > + * @block: the ISP configuration block to validate
> > + *
> > + * Defines the function prototype for the driver's callback to perform
> > + * driver-specific validation on each ISP block.
> > + */
> > +typedef int (*v4l2_params_validate_block)(struct device *dev,
> > +					  const struct v4l2_params_block_header *block);
> > +
> > +/**
> > + * v4l2_params_blocks_validate - Validate V4L2 extensible parameters ISP
> > + *				 configuration blocks
> > + * @dev: the driver's device pointer
> > + * @buffer: the extensible parameters configuration buffer
> > + * @handlers: the list of block handlers
> > + * @num_handlers: the number of block handlers
> > + * @block_validate: callback to the driver-specific per-block validation
> > + *		    function
> > + *
> > + * Helper function that performs validation of the ISP configuration blocks in
> > + * an extensible parameters buffer.
> > + *
> > + * The helper is meant to be used by drivers to perform validation of the
> > + * ISP configuration data blocks. For each block in the extensible parameters
> > + * buffer, its size and correctness are validated against its associated handler
> > + * in the @handlers list. Additionally, if provided, the @block_validate
> > + * callback is invoked on each block to allow drivers to perform driver-specific
> > + * validation.
> > + *
> > + * Drivers should use this function to validate the ISP configuration blocks
> > + * after having validated the correctness of the vb2 buffer sizes by using the
> > + * v4l2_params_buffer_validate() helper first. Once the buffer size has been
> > + * validated, drivers should perform a copy of the user-provided buffer into a
> > + * kernel-only memory buffer to prevent userspace from modifying the buffer
> > + * content after it has been submitted to the driver, and then call this
> > + * function to perform per-block validation.
> > + *
> > + * Examples of users of this function can be found in
> > + * rkisp1_params_prepare_ext_params() and in c3_isp_params_vb2_buf_prepare().
> > + */
> > +int v4l2_params_blocks_validate(struct device *dev,
> > +				const struct v4l2_params_buffer *buffer,
> > +				const struct v4l2_params_handler *handlers,
> > +				size_t num_handlers,
> > +				v4l2_params_validate_block block_validate);
> > +
> > +#endif /* V4L2_PARAMS_H_ */
> >
>
> --
> Regards,
>
> Sakari Ailus

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Re: [PATCH v3 5/8] media: v4l2-common: Introduce v4l2-params.c

[Sakari Ailus]

Hi Jacopo,

On Wed, Aug 20, 2025 at 09:11:06AM +0200, Jacopo Mondi wrote:
> Hi Sakari
> 
> On Wed, Aug 20, 2025 at 01:20:47AM +0300, Sakari Ailus wrote:
> > Hi Jacopo,
> >
> > In the subject:
> >
> > s/common/params/
> 
> I actually meant "media: v4l2-core:"

We've usually referred to the more specific part under
drivers/media/v4l2-core if a patch is touching just one of them, e.g.
v4l2-fwnode or v4l2-common.

-- 
Regards,

Sakari Ailus

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