[PATCH 0/2] media: i2c: Add ov2735 camera sensor driver

[PATCH 0/2] media: i2c: Add ov2735 camera sensor driver

[Hardevsinh Palaniya]

Add a v4l2 subdevice driver for the Omnivision OV2735 sensor.

The Omnivision OV2735 is a 1/2.7-Inch CMOS image sensor with an
active array size of 1920 x 1080.

The following features are supported:
- Manual exposure an gain control support
- vblank/hblank control support
- Test pattern support control
- Supported resolution: 1920 x 1080 @ 30fps (SGRBG10)

The driver is tested on mainline branch v6.14-rc6 on IMX8MP Debix Model a.

Hardevsinh Palaniya (2):
  dt-bindings: media: i2c: Add ov2735 sensor
  media: i2c: add ov2735 image sensor driver

 .../bindings/media/i2c/ovti,ov2735.yaml       | 104 ++
 drivers/media/i2c/Kconfig                     |  10 +
 drivers/media/i2c/Makefile                    |   1 +
 drivers/media/i2c/ov2735.c                    | 907 ++++++++++++++++++
 4 files changed, 1022 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/media/i2c/ovti,ov2735.yaml
 create mode 100644 drivers/media/i2c/ov2735.c

-- 
2.34.1

[PATCH 1/2] dt-bindings: media: i2c: Add ov2735 sensor

[Hardevsinh Palaniya]

Add bindings for Omnivision OV2735 sensor.

Signed-off-by: Himanshu Bhavani <himanshu.bhavani@siliconsignals.io>
Signed-off-by: Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.io>
---
 .../bindings/media/i2c/ovti,ov2735.yaml       | 104 ++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/media/i2c/ovti,ov2735.yaml

diff --git a/Documentation/devicetree/bindings/media/i2c/ovti,ov2735.yaml b/Documentation/devicetree/bindings/media/i2c/ovti,ov2735.yaml
new file mode 100644
index 000000000000..a6be7886f4d6
--- /dev/null
+++ b/Documentation/devicetree/bindings/media/i2c/ovti,ov2735.yaml
@@ -0,0 +1,104 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/media/i2c/ovti,ov2735.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: OmniVision OV2735 Image Sensor
+
+maintainers:
+  - Himanshu Bhavani <himanshu.bhavani@siliconsignals.io>
+
+description: |
+  The OmniVision OV2735 is a 2MP (1920x1080) color CMOS image sensor controlled
+  through an I2C-compatible SCCB bus. it outputs RAW10 format and uses a 1/2.7"
+  optical format.
+
+properties:
+  compatible:
+    const: ovti,ov2735
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: XVCLK clock
+
+  clock-names:
+    items:
+      - const: xvclk
+
+  AVDD-supply:
+    description: Analog Domain Power Supply
+
+  DOVDD-supply:
+    description: I/O Domain Power Supply
+
+  DVDD-supply:
+    description: Digital Domain Power Supply
+
+  reset-gpios:
+    maxItems: 1
+    description: Reset Pin GPIO Control (active low)
+
+  pwdn-gpios:
+    maxItems: 1
+    description: Powerdown Pin GPIO Control (active low)
+
+  port:
+    description: MIPI CSI-2 transmitter port
+    $ref: /schemas/graph.yaml#/$defs/port-base
+    additionalProperties: false
+
+    properties:
+      endpoint:
+        $ref: /schemas/media/video-interfaces.yaml#
+        unevaluatedProperties: false
+
+        properties:
+          data-lanes:
+            items:
+              - const: 1
+              - const: 2
+
+        required:
+          - data-lanes
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - port
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/rk3399-cru.h>
+    #include <dt-bindings/gpio/gpio.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        camera-sensor@3c {
+            compatible = "ovti,ov2735";
+            reg = <0x3c>;
+            clocks = <&ov2735_clk>;
+
+            assigned-clocks = <&ov2735_clk>;
+            assigned-clock-parents = <&ov2735_clk_parent>;
+            assigned-clock-rates = <24000000>;
+
+            reset-gpios = <&gpio1 6 GPIO_ACTIVE_LOW>;
+            pwdn-gpios = <&gpio2 11 GPIO_ACTIVE_LOW>;
+
+            port {
+                cam_out: endpoint {
+                    remote-endpoint = <&mipi_in_cam>;
+                    data-lanes = <1 2>;
+                };
+            };
+        };
+    };
-- 
2.34.1

[PATCH 2/2] media: i2c: add ov2735 image sensor driver

[Hardevsinh Palaniya]

Add a v4l2 subdevice driver for the Omnivision OV2735 sensor.

The Omnivision OV2735 is a 1/2.7-Inch CMOS image sensor with an
active array size of 1920 x 1080.

- Manual exposure an gain control support
- vblank/hblank control support
- Supported resolution: 1920 x 1080 @ 30fps (SGRBG10)

Co-developed-by: Himanshu Bhavani <himanshu.bhavani@siliconsignals.io>
Signed-off-by: Himanshu Bhavani <himanshu.bhavani@siliconsignals.io>
Signed-off-by: Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.io>
---
 drivers/media/i2c/Kconfig  |  10 +
 drivers/media/i2c/Makefile |   1 +
 drivers/media/i2c/ov2735.c | 907 +++++++++++++++++++++++++++++++++++++
 3 files changed, 918 insertions(+)
 create mode 100644 drivers/media/i2c/ov2735.c

diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index 4b4c199da6ea..9646eab1b177 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -446,6 +446,16 @@ config VIDEO_OV2685
 	  To compile this driver as a module, choose M here: the
 	  module will be called ov2685.
 
+config VIDEO_OV2735
+	tristate "OmniVision OV2735 sensor support"
+	select V4L2_CCI_I2C
+	help
+	  This is a Video4Linux2 sensor driver for the Sony
+	  OV2735 camera.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ov2735.
+
 config VIDEO_OV2740
 	tristate "OmniVision OV2740 sensor support"
 	depends on ACPI || COMPILE_TEST
diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
index 5873d29433ee..1adb27743fa1 100644
--- a/drivers/media/i2c/Makefile
+++ b/drivers/media/i2c/Makefile
@@ -93,6 +93,7 @@ obj-$(CONFIG_VIDEO_OV2640) += ov2640.o
 obj-$(CONFIG_VIDEO_OV2659) += ov2659.o
 obj-$(CONFIG_VIDEO_OV2680) += ov2680.o
 obj-$(CONFIG_VIDEO_OV2685) += ov2685.o
+obj-$(CONFIG_VIDEO_OV2735) += ov2735.o
 obj-$(CONFIG_VIDEO_OV2740) += ov2740.o
 obj-$(CONFIG_VIDEO_OV4689) += ov4689.o
 obj-$(CONFIG_VIDEO_OV5640) += ov5640.o
diff --git a/drivers/media/i2c/ov2735.c b/drivers/media/i2c/ov2735.c
new file mode 100644
index 000000000000..015b37bbfe88
--- /dev/null
+++ b/drivers/media/i2c/ov2735.c
@@ -0,0 +1,907 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * V4L2 Support for the OV2735
+ *
+ * Copyright (C) 2025 Silicon Signals Pvt. Ltd.
+ *
+ * Based on Rockchip ov2735 Camera Driver
+ * Copyright (C) 2017 Fuzhou Rockchip Electronics Co., Ltd.
+ *
+ * Inspired from ov8858, imx219, imx283 camera drivers
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
+#include <linux/units.h>
+
+#include <media/v4l2-cci.h>
+#include <media/v4l2-ctrls.h>
+#include <media/v4l2-device.h>
+#include <media/v4l2-fwnode.h>
+#include <media/v4l2-mediabus.h>
+
+#define OV2735_XCLK_FREQ			24000000
+
+#define OV2735_REG_PAGE_SELECT			CCI_REG8(0xfd)
+
+/* Page 0 */
+#define OV2735_REG_CHIPID			CCI_REG16(0x02)
+#define OV2735_CHIPID				0x2735
+
+#define OV2735_REG_SOFT_REST			CCI_REG8(0x20)
+
+/* Clock Settings */
+#define OV2735_REG_PLL_CTRL			CCI_REG8(0x2f)
+#define OV2735_REG_PLL_OUTDIV			CCI_REG8(0x34)
+#define OV2735_REG_CLK_MODE			CCI_REG8(0x30)
+#define OV2735_REG_CLOCK_REG1			CCI_REG8(0x33)
+#define OV2735_REG_CLOCK_REG2			CCI_REG8(0x35)
+
+/* Page 1 */
+#define OV2735_REG_STREAM_CTRL			CCI_REG8(0xa0)
+#define OV2735_STREAM_ON			0x01
+#define OV2735_STREAM_OFF			0x00
+
+#define OV2735_REG_UPDOWN_MIRROR		CCI_REG8(0x3f)
+#define OV2735_REG_BINNING_DAC_CODE_MODE	CCI_REG8(0x30)
+#define OV2735_REG_FRAME_LENGTH			CCI_REG16(0x0e)
+#define OV2735_VTS_MAX				0x0fff
+#define OV2735_REG_FRAME_EXP_SEPERATE_EN	CCI_REG8(0x0d)
+#define OV2735_FRAME_EXP_SEPERATE_EN		0x10
+#define OV2735_REG_FRAME_SYNC			CCI_REG8(0x01)
+
+#define OV2735_REG_HBLANK			CCI_REG16(0x09)
+
+#define OV2735_REG_HS_MIPI			CCI_REG8(0xb1)
+#define OV2735_REG_MIPI_CTRL1			CCI_REG8(0x92)
+#define OV2735_REG_MIPI_CTRL2			CCI_REG8(0x94)
+#define OV2735_REG_MIPI_CTRL3			CCI_REG8(0xa1)
+#define OV2735_REG_MIPI_CTRL4			CCI_REG8(0xb2)
+#define OV2735_REG_MIPI_CTRL5			CCI_REG8(0xb3)
+#define OV2735_REG_MIPI_CTRL6			CCI_REG8(0xb4)
+#define OV2735_REG_MIPI_CTRL7			CCI_REG8(0xb5)
+#define OV2735_REG_PREPARE			CCI_REG8(0x95)
+#define OV2735_REG_R_HS_ZERO			CCI_REG8(0x96)
+#define OV2735_REG_TRAIL			CCI_REG8(0x98)
+#define OV2735_REG_R_CLK_ZERO			CCI_REG8(0x9c)
+#define OV2735_REG_MIPI_V_SIZE			CCI_REG16(0x8e)
+#define OV2735_REG_MIPI_H_SIZE			CCI_REG16(0x90)
+
+#define OV2735_REG_ANALOG_CTRL3			CCI_REG8(0x25)
+#define OV2735_REG_VNCP				CCI_REG8(0x20)
+
+/* BLC registers */
+#define OV2735_REG_BLC_GAIN_BLUE		CCI_REG8(0x86)
+#define OV2735_REG_BLC_GAIN_RED			CCI_REG8(0x87)
+#define OV2735_REG_BLC_GAIN_GR			CCI_REG8(0x88)
+#define OV2735_REG_BLC_GAIN_GB			CCI_REG8(0x89)
+#define OV2735_REG_GB_SUBOFFSET			CCI_REG8(0xf0)
+#define OV2735_REG_BLUE_SUBOFFSET		CCI_REG8(0xf1)
+#define OV2735_REG_RED_SUBOFFSET		CCI_REG8(0xf2)
+#define OV2735_REG_GR_SUBOFFSET			CCI_REG8(0xf3)
+#define OV2735_REG_BLC_BPC_TH_P			CCI_REG8(0xfc)
+#define OV2735_REG_BLC_BPC_TH_N			CCI_REG8(0xfe)
+
+#define OV2735_REG_TEST_PATTERN			CCI_REG8(0xb2)
+#define OV2735_TEST_PATTERN_ENABLE		0x01
+#define OV2735_TEST_PATTERN_DISABLE		0xfe
+
+#define OV2735_REG_LONG_EXPOSURE		CCI_REG16(0x03)
+#define	OV2735_EXPOSURE_MIN			4
+#define	OV2735_EXPOSURE_STEP			1
+
+#define OV2735_REG_ANALOG_GAIN                  CCI_REG8(0x24)
+#define	ANALOG_GAIN_MIN				0x10
+#define	ANALOG_GAIN_MAX				0xff
+#define	ANALOG_GAIN_STEP			1
+#define	ANALOG_GAIN_DEFAULT			0x10
+
+/* Page 2 */
+#define OV2735_REG_V_START			CCI_REG16(0xa0)
+#define OV2735_REG_V_SIZE			CCI_REG16(0xa2)
+#define OV2735_REG_H_START			CCI_REG16(0xa4)
+#define OV2735_REG_H_SIZE			CCI_REG16(0xa6)
+
+#define OV2735_LINK_FREQ_420MHZ			420000000
+#define OV2735_PIXEL_RATE			168000000
+
+static const char * const ov2735_supply_name[] = {
+	"AVDD",		/* Analog power */
+	"DOVDD",	/* Digital I/O power */
+	"DVDD",		/* Digital core power */
+};
+
+struct ov2735 {
+	struct device *dev;
+	struct regmap *cci;
+	struct v4l2_subdev sd;
+	struct media_pad pad;
+	struct i2c_client *client;
+	struct clk *xclk;
+	struct gpio_desc *reset_gpio;
+	struct gpio_desc *pwdn_gpio;
+	struct regulator_bulk_data supplies[ARRAY_SIZE(ov2735_supply_name)];
+
+	/* V4L2 Controls */
+	struct v4l2_ctrl_handler handler;
+	struct v4l2_ctrl *link_freq;
+	struct v4l2_ctrl *pixel_rate;
+	struct v4l2_ctrl *hblank;
+	struct v4l2_ctrl *vblank;
+	struct v4l2_ctrl *gain;
+	struct v4l2_ctrl *exposure;
+	struct v4l2_ctrl *test_pattern;
+};
+
+struct ov2735_reglist {
+	unsigned int num_regs;
+	const struct cci_reg_sequence *regvals;
+};
+
+struct ov2735_mode {
+	u32 width;
+	u32 height;
+	u32 hts_def;
+	u32 vts_def;
+	u32 exp_def;
+	struct ov2735_reglist reg_list;
+};
+
+static struct cci_reg_sequence ov2735_1920_1080_30fps[] = {
+	{ OV2735_REG_PAGE_SELECT,		0x00 },
+	{ OV2735_REG_PLL_CTRL,			0x10 },
+	{ OV2735_REG_PLL_OUTDIV,		0x00 },
+	{ OV2735_REG_CLK_MODE,			0x15 },
+	{ OV2735_REG_CLOCK_REG1,		0x01 },
+	{ OV2735_REG_CLOCK_REG2,		0x20 },
+	{ OV2735_REG_PAGE_SELECT,		0x01 },
+	{ OV2735_REG_BINNING_DAC_CODE_MODE,	0x00 },
+	{ CCI_REG8(0xfb),			0x73 },
+	{ OV2735_REG_FRAME_SYNC,		0x01 },
+	{ OV2735_REG_PAGE_SELECT,		0x01 },
+
+	/* Timing ctrl */
+	{ CCI_REG8(0x1a), 0x6b },
+	{ CCI_REG8(0x1c), 0xea },
+	{ CCI_REG8(0x16), 0x0c },
+	{ CCI_REG8(0x21), 0x00 },
+	{ CCI_REG8(0x11), 0x63 },
+	{ CCI_REG8(0x19), 0xc3 },
+
+	/* Analog ctrl */
+	{ CCI_REG8(0x26), 0x5a },
+	{ CCI_REG8(0x29), 0x01 },
+	{ CCI_REG8(0x33), 0x6f },
+	{ CCI_REG8(0x2a), 0xd2 },
+	{ CCI_REG8(0x2c), 0x40 },
+	{ CCI_REG8(0xd0), 0x02 },
+	{ CCI_REG8(0xd1), 0x01 },
+	{ CCI_REG8(0xd2), 0x20 },
+	{ CCI_REG8(0xd3), 0x04 },
+	{ CCI_REG8(0xd4), 0x2a },
+	{ CCI_REG8(0x50), 0x00 },
+	{ CCI_REG8(0x51), 0x2c },
+	{ CCI_REG8(0x52), 0x29 },
+	{ CCI_REG8(0x53), 0x00 },
+	{ CCI_REG8(0x55), 0x44 },
+	{ CCI_REG8(0x58), 0x29 },
+	{ CCI_REG8(0x5a), 0x00 },
+	{ CCI_REG8(0x5b), 0x00 },
+	{ CCI_REG8(0x5d), 0x00 },
+	{ CCI_REG8(0x64), 0x2f },
+	{ CCI_REG8(0x66), 0x62 },
+	{ CCI_REG8(0x68), 0x5b },
+	{ CCI_REG8(0x75), 0x46 },
+	{ CCI_REG8(0x76), 0x36 },
+	{ CCI_REG8(0x77), 0x4f },
+	{ CCI_REG8(0x78), 0xef },
+	{ CCI_REG8(0x72), 0xcf },
+	{ CCI_REG8(0x73), 0x36 },
+	{ CCI_REG8(0x7d), 0x0d },
+	{ CCI_REG8(0x7e), 0x0d },
+	{ CCI_REG8(0x8a), 0x77 },
+	{ CCI_REG8(0x8b), 0x77 },
+
+	{ OV2735_REG_PAGE_SELECT,	0x01 },
+	{ OV2735_REG_HS_MIPI,		0x83 },
+	{ OV2735_REG_MIPI_CTRL5,	0x0b },
+	{ OV2735_REG_MIPI_CTRL6,	0x14 },
+	{ CCI_REG8(0x9d),		0x40 },
+	{ OV2735_REG_MIPI_CTRL3,	0x05 },
+	{ OV2735_REG_MIPI_CTRL2,	0x44 },
+	{ OV2735_REG_PREPARE,		0x33 },
+	{ OV2735_REG_R_HS_ZERO,	0x1f },
+	{ OV2735_REG_TRAIL,		0x45 },
+	{ OV2735_REG_R_CLK_ZERO,	0x10 },
+	{ OV2735_REG_MIPI_CTRL7,	0x70 },
+	{ OV2735_REG_ANALOG_CTRL3,	0xe0 },
+	{ OV2735_REG_VNCP,		0x7b },
+
+	/* BLC */
+	{ OV2735_REG_PAGE_SELECT,	0x01 },
+	{ OV2735_REG_BLC_GAIN_BLUE,	0x77 },
+	{ OV2735_REG_BLC_GAIN_GB,	0x77 },
+	{ OV2735_REG_BLC_GAIN_RED,	0x74 },
+	{ OV2735_REG_BLC_GAIN_GR,	0x74 },
+	{ OV2735_REG_BLC_BPC_TH_P,	0xe0 },
+	{ OV2735_REG_BLC_BPC_TH_N,	0xe0 },
+	{ OV2735_REG_GB_SUBOFFSET,	0x40 },
+	{ OV2735_REG_BLUE_SUBOFFSET,	0x40 },
+	{ OV2735_REG_RED_SUBOFFSET,	0x40 },
+	{ OV2735_REG_GR_SUBOFFSET,	0x40 },
+
+	/* 1920x1080 */
+	{ OV2735_REG_PAGE_SELECT,	0x02 },
+	{ OV2735_REG_V_START,		0x0008 },
+	{ OV2735_REG_V_SIZE,		0x0438 },
+	{ OV2735_REG_H_START,		0x0008 },
+	{ OV2735_REG_H_SIZE,		0x03c0 },
+	{ OV2735_REG_PAGE_SELECT,	0x01 },
+	{ OV2735_REG_MIPI_V_SIZE,	0x0780 },
+	{ OV2735_REG_MIPI_H_SIZE,	0x0438 },
+};
+
+static const struct ov2735_mode supported_modes[] = {
+	{
+		.width = 1920,
+		.height = 1080,
+		.exp_def = 399,
+		.hts_def = 2200,
+		.vts_def = 2545,
+		.reg_list = {
+			.num_regs = ARRAY_SIZE(ov2735_1920_1080_30fps),
+			.regvals = ov2735_1920_1080_30fps,
+		},
+	},
+};
+
+static const s64 link_freq_menu_items[] = {
+	OV2735_LINK_FREQ_420MHZ
+};
+
+static const char * const ov2735_test_pattern_menu[] = {
+	"Disabled",
+	"Vertical Color",
+};
+
+static const u32 ov2735_mbus_codes[] = {
+	MEDIA_BUS_FMT_SGRBG10_1X10,
+};
+
+static inline struct ov2735 *to_ov2735(struct v4l2_subdev *_sd)
+{
+	return container_of(_sd, struct ov2735, sd);
+}
+
+static int ov2735_enable_test_pattern(struct ov2735 *ov2735, u32 pattern)
+{
+	int ret;
+	u64 val;
+
+	ret = cci_read(ov2735->cci, OV2735_REG_TEST_PATTERN, &val, NULL);
+	if (ret)
+		return ret;
+
+	switch (pattern) {
+	case 0:
+		val &= ~OV2735_TEST_PATTERN_ENABLE;
+		break;
+	case 1:
+		val |= OV2735_TEST_PATTERN_ENABLE;
+		break;
+	}
+
+	ret = cci_write(ov2735->cci, OV2735_REG_TEST_PATTERN, val, NULL);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ov2735_set_ctrl(struct v4l2_ctrl *ctrl)
+{
+	struct ov2735 *ov2735 = container_of(ctrl->handler, struct ov2735,
+					     handler);
+	const struct ov2735_mode *mode;
+	struct v4l2_mbus_framefmt *fmt;
+	struct v4l2_subdev_state *state;
+	int vts;
+	int ret = 0;
+
+	state = v4l2_subdev_get_locked_active_state(&ov2735->sd);
+	fmt = v4l2_subdev_state_get_format(state, 0);
+
+	mode = v4l2_find_nearest_size(supported_modes,
+				      ARRAY_SIZE(supported_modes),
+				      width, height,
+				      fmt->width, fmt->height);
+
+	if (ctrl->id == V4L2_CID_VBLANK) {
+		/* Honour the VBLANK limits when setting exposure. */
+		s64 max = mode->height + ctrl->val - 4;
+
+		ret = __v4l2_ctrl_modify_range(ov2735->exposure,
+					       ov2735->exposure->minimum, max,
+					 ov2735->exposure->step,
+					 ov2735->exposure->default_value);
+		if (ret)
+			return ret;
+	}
+
+	/*
+	 * Applying V4L2 control value only happens
+	 * when power is up for streaming
+	 */
+	if (pm_runtime_get_if_in_use(ov2735->dev) == 0)
+		return 0;
+
+	ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
+
+	switch (ctrl->id) {
+	case V4L2_CID_EXPOSURE:
+		ret |= cci_write(ov2735->cci, OV2735_REG_LONG_EXPOSURE, ctrl->val, NULL);
+		break;
+	case V4L2_CID_ANALOGUE_GAIN:
+		ret |= cci_write(ov2735->cci, OV2735_REG_ANALOG_GAIN, ctrl->val, NULL);
+		break;
+	case V4L2_CID_HBLANK:
+		ret |= cci_write(ov2735->cci, OV2735_REG_HBLANK, ctrl->val, NULL);
+		break;
+	case V4L2_CID_VBLANK:
+		vts = ctrl->val + mode->height;
+		ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_EXP_SEPERATE_EN,
+				 OV2735_FRAME_EXP_SEPERATE_EN, NULL);
+		ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_LENGTH, vts, NULL);
+		break;
+	case V4L2_CID_TEST_PATTERN:
+		ret = ov2735_enable_test_pattern(ov2735, ctrl->val);
+		break;
+	default:
+		dev_err(ov2735->dev, "ctrl(id:0x%x, val:0x%x) is not handled\n",
+			ctrl->id, ctrl->val);
+		break;
+	}
+	ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_SYNC, 0x01, NULL);
+
+	pm_runtime_put(ov2735->dev);
+
+	return ret;
+}
+
+static const struct v4l2_ctrl_ops ov2735_ctrl_ops = {
+	.s_ctrl = ov2735_set_ctrl,
+};
+
+static int ov2735_init_controls(struct ov2735 *ov2735)
+{
+	struct v4l2_ctrl_handler *ctrl_hdlr;
+	struct v4l2_fwnode_device_properties props;
+	const struct ov2735_mode *mode = &supported_modes[0];
+	u64 hblank_def, vblank_def, exp_max;
+	int ret;
+
+	ctrl_hdlr = &ov2735->handler;
+	ret = v4l2_ctrl_handler_init(ctrl_hdlr, 7);
+	if (ret)
+		return ret;
+
+	ov2735->pixel_rate = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops, V4L2_CID_PIXEL_RATE,
+					       0, OV2735_PIXEL_RATE, 1, OV2735_PIXEL_RATE); 
+
+	ov2735->link_freq = v4l2_ctrl_new_int_menu(ctrl_hdlr, &ov2735_ctrl_ops,
+						   V4L2_CID_LINK_FREQ,
+						   0, 0, link_freq_menu_items);
+	if (ov2735->link_freq)
+		ov2735->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
+
+	hblank_def =  mode->hts_def - mode->width;
+	ov2735->hblank = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops, V4L2_CID_HBLANK,
+					   hblank_def, hblank_def, 1, hblank_def);
+
+	vblank_def = mode->vts_def - mode->height;
+	ov2735->vblank = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
+					   V4L2_CID_VBLANK, vblank_def,
+				OV2735_VTS_MAX - mode->height,
+				1, vblank_def);
+
+	exp_max = mode->vts_def - 4;
+	ov2735->exposure = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
+					     V4L2_CID_EXPOSURE, OV2735_EXPOSURE_MIN,
+				exp_max, OV2735_EXPOSURE_STEP, mode->exp_def);
+
+	ov2735->gain = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
+					 V4L2_CID_ANALOGUE_GAIN, ANALOG_GAIN_MIN,
+				ANALOG_GAIN_MAX, ANALOG_GAIN_STEP,
+				ANALOG_GAIN_DEFAULT);
+
+	ov2735->test_pattern = v4l2_ctrl_new_std_menu_items(ctrl_hdlr,
+							    &ov2735_ctrl_ops, V4L2_CID_TEST_PATTERN,
+			ARRAY_SIZE(ov2735_test_pattern_menu) - 1,
+			0, 0, ov2735_test_pattern_menu);
+
+	if (ctrl_hdlr->error) {
+		ret = ctrl_hdlr->error;
+		dev_err(ov2735->dev, "control init failed (%d)\n", ret);
+		goto error;
+	}
+
+	ret = v4l2_fwnode_device_parse(ov2735->dev, &props);
+	if (ret)
+		goto error;
+
+	ret = v4l2_ctrl_new_fwnode_properties(ctrl_hdlr, &ov2735_ctrl_ops,
+					      &props);
+	if (ret)
+		goto error;
+
+	ov2735->sd.ctrl_handler = ctrl_hdlr;
+
+	return 0;
+error:
+	v4l2_ctrl_handler_free(ctrl_hdlr);
+
+	return ret;
+}
+
+static int ov2735_enable_streams(struct v4l2_subdev *sd,
+				 struct v4l2_subdev_state *state, u32 pad,
+				u64 streams_mask)
+{
+	struct ov2735 *ov2735 = to_ov2735(sd);
+	const struct ov2735_mode *mode;
+	const struct ov2735_reglist *reg_list;
+	const struct v4l2_mbus_framefmt *fmt;
+	int ret = 0;
+
+	fmt = v4l2_subdev_state_get_format(state, 0);
+	mode = v4l2_find_nearest_size(supported_modes,
+				      ARRAY_SIZE(supported_modes),
+				      width, height,
+				      fmt->width, fmt->height);
+
+	ret = pm_runtime_resume_and_get(ov2735->dev);
+	if (ret < 0)
+		return ret;
+
+	reg_list = &mode->reg_list;
+	ret = cci_multi_reg_write(ov2735->cci, reg_list->regvals, reg_list->num_regs, NULL);
+	if (ret) {
+		dev_err(ov2735->dev, "%s failed to send mfg header\n", __func__);
+		goto err_rpm_put;
+	}
+
+	/* Apply customized values from user */
+	ret =  __v4l2_ctrl_handler_setup(ov2735->sd.ctrl_handler);
+	if (ret)
+		goto err_rpm_put;
+
+	/* set stream on register */
+	ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
+	ret |= cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_ON, NULL);
+	if (ret)
+		goto err_rpm_put;
+
+	return 0;
+
+err_rpm_put:
+	pm_runtime_put(ov2735->dev);
+	return ret;
+}
+
+static int ov2735_disable_streams(struct v4l2_subdev *sd,
+				  struct v4l2_subdev_state *state, u32 pad,
+				  u64 streams_mask)
+{
+	struct ov2735 *ov2735 = to_ov2735(sd);
+	int ret = 0;
+
+	/* set stream off register */
+	ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
+	ret |= cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_OFF, NULL);
+	if (ret)
+		dev_err(ov2735->dev, "%s failed to set stream\n", __func__);
+
+	pm_runtime_put(ov2735->dev);
+
+	return ret;
+}
+
+static int ov2735_enum_mbus_code(struct v4l2_subdev *sd,
+				 struct v4l2_subdev_state *sd_state,
+				 struct v4l2_subdev_mbus_code_enum *code)
+{
+	if (code->index >= ARRAY_SIZE(ov2735_mbus_codes))
+		return -EINVAL;
+
+	code->code = ov2735_mbus_codes[code->index];
+
+	return 0;
+}
+
+static int ov2735_enum_frame_size(struct v4l2_subdev *sd,
+				  struct v4l2_subdev_state *sd_state,
+				   struct v4l2_subdev_frame_size_enum *fse)
+{
+	u32 code;
+
+	if (fse->index >= ARRAY_SIZE(supported_modes))
+		return -EINVAL;
+
+	code = MEDIA_BUS_FMT_SGRBG10_1X10;
+	if (fse->code != code)
+		return -EINVAL;
+
+	fse->min_width = supported_modes[fse->index].width;
+	fse->max_width = fse->min_width;
+	fse->min_height = supported_modes[fse->index].height;
+	fse->max_height = fse->min_height;
+
+	return 0;
+}
+
+static void ov2735_set_framing_limits(struct ov2735 *ov2735,
+				      const struct ov2735_mode *mode)
+{
+	u32 hblank, vblank_def;
+
+	hblank = mode->hts_def - mode->width;
+	__v4l2_ctrl_modify_range(ov2735->hblank, hblank, hblank, 1, hblank);
+
+	vblank_def = mode->vts_def - mode->height;
+	__v4l2_ctrl_modify_range(ov2735->vblank, vblank_def, OV2735_VTS_MAX - mode->height,
+				 1, vblank_def);
+}
+
+static int ov2735_set_pad_format(struct v4l2_subdev *sd,
+				 struct v4l2_subdev_state *sd_state,
+				 struct v4l2_subdev_format *fmt)
+{
+	struct v4l2_mbus_framefmt *format;
+	const struct ov2735_mode *mode;
+	struct ov2735 *ov2735 = to_ov2735(sd);
+
+	format = v4l2_subdev_state_get_format(sd_state, 0);
+
+	mode = v4l2_find_nearest_size(supported_modes,
+				      ARRAY_SIZE(supported_modes),
+			      width, height,
+			      fmt->format.width, fmt->format.height);
+
+	fmt->format.width = mode->width;
+	fmt->format.height = mode->height;
+	fmt->format.field = V4L2_FIELD_NONE;
+	fmt->format.colorspace = V4L2_COLORSPACE_RAW;
+	fmt->format.quantization = V4L2_QUANTIZATION_FULL_RANGE;
+	fmt->format.xfer_func = V4L2_XFER_FUNC_NONE;
+
+	format = v4l2_subdev_state_get_format(sd_state, 0);
+
+	if (fmt->which == V4L2_SUBDEV_FORMAT_ACTIVE)
+		ov2735_set_framing_limits(ov2735, mode);
+
+	*format = fmt->format;
+
+	return 0;
+}
+
+static int ov2735_init_state(struct v4l2_subdev *sd,
+			     struct v4l2_subdev_state *state)
+{
+	struct v4l2_subdev_format fmt = {
+		.which = V4L2_SUBDEV_FORMAT_TRY,
+		.pad = 0,
+		.format = {
+			.code = MEDIA_BUS_FMT_SGRBG10_1X10,
+			.width = supported_modes[0].width,
+			.height = supported_modes[0].height,
+		},
+	};
+
+	ov2735_set_pad_format(sd, state, &fmt);
+
+	return 0;
+}
+
+static const struct v4l2_subdev_video_ops ov2735_video_ops = {
+	.s_stream = v4l2_subdev_s_stream_helper,
+};
+
+static const struct v4l2_subdev_pad_ops ov2735_pad_ops = {
+	.enum_mbus_code = ov2735_enum_mbus_code,
+	.get_fmt = v4l2_subdev_get_fmt,
+	.set_fmt = ov2735_set_pad_format,
+	.enum_frame_size = ov2735_enum_frame_size,
+	.enable_streams = ov2735_enable_streams,
+	.disable_streams = ov2735_disable_streams,
+};
+
+static const struct v4l2_subdev_ops ov2735_subdev_ops = {
+	.video = &ov2735_video_ops,
+	.pad = &ov2735_pad_ops,
+};
+
+static const struct v4l2_subdev_internal_ops ov2735_internal_ops = {
+	.init_state = ov2735_init_state,
+};
+
+static int ov2735_power_on(struct device *dev)
+{
+	struct v4l2_subdev *sd = dev_get_drvdata(dev);
+	struct ov2735 *ov2735 = to_ov2735(sd);
+	int ret;
+	unsigned long delay_us;
+
+	gpiod_set_value_cansleep(ov2735->pwdn_gpio, 0);
+	usleep_range(2000, 5000);
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(ov2735_supply_name),
+				    ov2735->supplies);
+	if (ret) {
+		dev_err(ov2735->dev, "failed to enable regulators\n");
+		return ret;
+	}
+
+	gpiod_set_value_cansleep(ov2735->pwdn_gpio, 1);
+	usleep_range(2000, 5000);
+
+	gpiod_set_value_cansleep(ov2735->reset_gpio, 0);
+	usleep_range(2000, 5000);
+
+	ret = clk_prepare_enable(ov2735->xclk);
+	if (ret) {
+		dev_err(ov2735->dev, "failed to enable clock\n");
+		goto regulator_off;
+	}
+
+	/* 8192 cycles prior to first SCCB transaction */
+	delay_us = DIV_ROUND_UP(8192, OV2735_XCLK_FREQ / 1000 / 1000);
+	usleep_range(delay_us, delay_us * 2);
+
+	return 0;
+
+regulator_off:
+	regulator_bulk_disable(ARRAY_SIZE(ov2735_supply_name), ov2735->supplies);
+	return ret;
+}
+
+static int ov2735_power_off(struct device *dev)
+{
+	struct v4l2_subdev *sd = dev_get_drvdata(dev);
+	struct ov2735 *ov2735 = to_ov2735(sd);
+
+	gpiod_set_value_cansleep(ov2735->pwdn_gpio, 1);
+	clk_disable_unprepare(ov2735->xclk);
+	gpiod_set_value_cansleep(ov2735->reset_gpio, 0);
+	regulator_bulk_disable(ARRAY_SIZE(ov2735_supply_name), ov2735->supplies);
+
+	return 0;
+}
+
+static int ov2735_get_regulators(struct ov2735 *ov2735)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(ov2735_supply_name); i++)
+		ov2735->supplies[i].supply = ov2735_supply_name[i];
+
+	return devm_regulator_bulk_get(ov2735->dev,
+				       ARRAY_SIZE(ov2735_supply_name),
+				       ov2735->supplies);
+}
+
+static int ov2735_identify_module(struct ov2735 *ov2735)
+{
+	u64 chip_id;
+	int ret = 0;
+
+	ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x00, NULL);
+	ret |= cci_read(ov2735->cci, OV2735_REG_CHIPID, &chip_id, NULL);
+	if (ret)
+		return dev_err_probe(ov2735->dev, ret, "failed to read chip id %x\n",
+				     OV2735_CHIPID);
+
+	if (chip_id != OV2735_CHIPID)
+		return dev_err_probe(ov2735->dev, -EIO, "chip id mismatch: %x!=%llx\n",
+				     OV2735_CHIPID, chip_id);
+
+	return 0;
+}
+
+static int ov2735_parse_endpoint(struct ov2735 *ov2735)
+{
+	struct fwnode_handle *fwnode;
+	struct v4l2_fwnode_endpoint bus_cfg = {
+		.bus_type = V4L2_MBUS_CSI2_DPHY
+	};
+	struct fwnode_handle *ep;
+	int ret;
+
+	fwnode = dev_fwnode(ov2735->dev);
+	ep = fwnode_graph_get_next_endpoint(fwnode, NULL);
+	if (!ep) {
+		dev_err(ov2735->dev, "Failed to get next endpoint\n");
+		return -ENXIO;
+	}
+
+	ret = v4l2_fwnode_endpoint_alloc_parse(ep, &bus_cfg);
+	fwnode_handle_put(ep);
+	if (ret)
+		return ret;
+
+	if (bus_cfg.bus.mipi_csi2.num_data_lanes != 2) {
+		dev_err_probe(ov2735->dev, -EINVAL, "only 2 data lanes are supported\n");
+		goto error_out;
+	}
+
+	return 0;
+
+error_out:
+	v4l2_fwnode_endpoint_free(&bus_cfg);
+
+	return ret;
+};
+
+static int ov2735_probe(struct i2c_client *client)
+{
+	struct ov2735 *ov2735;
+	unsigned int xclk_freq;
+	int ret;
+
+	ov2735 = devm_kzalloc(&client->dev, sizeof(*ov2735), GFP_KERNEL);
+	if (!ov2735)
+		return -ENOMEM;
+
+	ov2735->client = client;
+	ov2735->dev = &client->dev;
+
+	v4l2_i2c_subdev_init(&ov2735->sd, client, &ov2735_subdev_ops);
+	ov2735->sd.internal_ops = &ov2735_internal_ops;
+
+	ov2735->cci = devm_cci_regmap_init_i2c(client, 8);
+	if (IS_ERR(ov2735->cci)) {
+		ret = PTR_ERR(ov2735->cci);
+		dev_err(ov2735->dev, "failed to initialize CCI: %d\n", ret);
+		return ret;
+	}
+
+	/* Get system clock (xclk) */
+	ov2735->xclk = devm_clk_get(ov2735->dev, NULL);
+	if (IS_ERR(ov2735->xclk)) {
+		return dev_err_probe(ov2735->dev, PTR_ERR(ov2735->xclk),
+				     "failed to get xclk\n");
+	}
+
+	xclk_freq = clk_get_rate(ov2735->xclk);
+	if (xclk_freq != OV2735_XCLK_FREQ)
+		return dev_err_probe(ov2735->dev, -EINVAL,
+				     "xclk frequency not supported: %d Hz\n",
+				     xclk_freq);
+
+	ret = ov2735_get_regulators(ov2735);
+	if (ret)
+		return dev_err_probe(ov2735->dev, ret, "failed to get regulators\n");
+
+	ret = ov2735_parse_endpoint(ov2735);
+	if (ret) {
+		dev_err(ov2735->dev, "failed to parse endpoint configuration\n");
+		return ret;
+	}
+
+	ov2735->reset_gpio = devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(ov2735->reset_gpio))
+		return dev_err_probe(ov2735->dev, PTR_ERR(ov2735->reset_gpio),
+				     "failed to get reset GPIO\n");
+
+	ov2735->pwdn_gpio = devm_gpiod_get(&client->dev, "pwdn", GPIOD_OUT_LOW);
+	if (IS_ERR(ov2735->pwdn_gpio))
+		return dev_err_probe(ov2735->dev, PTR_ERR(ov2735->pwdn_gpio),
+				     "failed to get reset GPIO\n");
+
+	ret = ov2735_power_on(ov2735->dev);
+	if (ret)
+		return ret;
+
+	ret = ov2735_identify_module(ov2735);
+	if (ret)
+		goto error_power_off;
+
+	/* This needs the pm runtime to be registered. */
+	ret = ov2735_init_controls(ov2735);
+	if (ret)
+		goto error_power_off;
+
+	/* Initialize subdev */
+	ov2735->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
+	ov2735->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
+	ov2735->pad.flags = MEDIA_PAD_FL_SOURCE;
+
+	ret = media_entity_pads_init(&ov2735->sd.entity, 1, &ov2735->pad);
+	if (ret) {
+		dev_err_probe(ov2735->dev, ret, "failed to init entity pads\n");
+		goto error_handler_free;
+	}
+
+	ov2735->sd.state_lock = ov2735->handler.lock;
+	ret = v4l2_subdev_init_finalize(&ov2735->sd);
+	if (ret < 0) {
+		dev_err_probe(ov2735->dev, ret, "subdev init error\n");
+		goto error_media_entity;
+	}
+
+	pm_runtime_set_active(ov2735->dev);
+	pm_runtime_enable(ov2735->dev);
+
+	ret = v4l2_async_register_subdev_sensor(&ov2735->sd);
+	if (ret < 0) {
+		dev_err_probe(ov2735->dev, ret,
+			      "failed to register ov2735 sub-device\n");
+		goto error_subdev_cleanup;
+	}
+
+	pm_runtime_idle(ov2735->dev);
+
+	return 0;
+
+error_subdev_cleanup:
+	v4l2_subdev_cleanup(&ov2735->sd);
+	pm_runtime_disable(ov2735->dev);
+	pm_runtime_set_suspended(ov2735->dev);
+
+error_media_entity:
+	media_entity_cleanup(&ov2735->sd.entity);
+
+error_handler_free:
+	v4l2_ctrl_handler_free(ov2735->sd.ctrl_handler);
+
+error_power_off:
+	ov2735_power_off(ov2735->dev);
+
+	return ret;
+}
+
+static void ov2735_remove(struct i2c_client *client)
+{
+	struct v4l2_subdev *sd = i2c_get_clientdata(client);
+	struct ov2735 *ov2735 = to_ov2735(sd);
+
+	v4l2_async_unregister_subdev(sd);
+	v4l2_subdev_cleanup(&ov2735->sd);
+	media_entity_cleanup(&sd->entity);
+	v4l2_ctrl_handler_free(ov2735->sd.ctrl_handler);
+
+	pm_runtime_disable(ov2735->dev);
+	if (!pm_runtime_status_suspended(ov2735->dev))
+		ov2735_power_off(ov2735->dev);
+	pm_runtime_set_suspended(ov2735->dev);
+}
+
+static DEFINE_RUNTIME_DEV_PM_OPS(ov2735_pm_ops, ov2735_power_off,
+				 ov2735_power_on, NULL);
+
+static const struct of_device_id ov2735_id[] = {
+	{ .compatible = "ovti,ov2735" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ov2735_id);
+
+static struct i2c_driver ov2735_driver = {
+	.driver = {
+		.name = "ov2735",
+		.pm = pm_ptr(&ov2735_pm_ops),
+		.of_match_table = ov2735_id,
+
+	},
+	.probe = ov2735_probe,
+	.remove = ov2735_remove,
+};
+
+module_i2c_driver(ov2735_driver);
+
+MODULE_DESCRIPTION("OV2735 Camera Sensor Driver");
+MODULE_AUTHOR("Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.io>");
+MODULE_AUTHOR("Himanshu Bhavani <himanshu.bhavani@siliconsignals.io>");
+MODULE_LICENSE("GPL");
-- 
2.34.1

Re: [PATCH 2/2] media: i2c: add ov2735 image sensor driver

[Andy Shevchenko]

On Mon, Jul 07, 2025 at 08:31:06PM +0530, Hardevsinh Palaniya wrote:
> Add a v4l2 subdevice driver for the Omnivision OV2735 sensor.
> 
> The Omnivision OV2735 is a 1/2.7-Inch CMOS image sensor with an
> active array size of 1920 x 1080.
> 
> - Manual exposure an gain control support
> - vblank/hblank control support
> - Supported resolution: 1920 x 1080 @ 30fps (SGRBG10)

...

> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/units.h>

More stuff is in use than just these headers provide.
E.g.,

+ array_size.h
+ container_of.h
+ gpio/consumer.h
+ types.h

And so on... Also in some cases the forward declarations are enough to have.

.,,

> +#define OV2735_LINK_FREQ_420MHZ			420000000

HZ_PER_MHZ ?

...

> +#define OV2735_PIXEL_RATE			168000000

What's the unit?

...

> +static const s64 link_freq_menu_items[] = {
> +	OV2735_LINK_FREQ_420MHZ

Keep the trailing comma like you have done in other cases.

> +};

...

> +static int ov2735_enable_test_pattern(struct ov2735 *ov2735, u32 pattern)
> +{
> +	int ret;
> +	u64 val;
> +
> +	ret = cci_read(ov2735->cci, OV2735_REG_TEST_PATTERN, &val, NULL);
> +	if (ret)
> +		return ret;
> +
> +	switch (pattern) {
> +	case 0:
> +		val &= ~OV2735_TEST_PATTERN_ENABLE;
> +		break;
> +	case 1:
> +		val |= OV2735_TEST_PATTERN_ENABLE;
> +		break;
> +	}

> +	ret = cci_write(ov2735->cci, OV2735_REG_TEST_PATTERN, val, NULL);
> +	if (ret)
> +		return ret;
> +
> +	return 0;

Is this the required style? Because these 5 LoCs is just a simple

	return cci_write(ov2735->cci, OV2735_REG_TEST_PATTERN, val, NULL);

> +}

...

> +static int ov2735_set_ctrl(struct v4l2_ctrl *ctrl)
> +{
> +	struct ov2735 *ov2735 = container_of(ctrl->handler, struct ov2735,
> +					     handler);
> +	const struct ov2735_mode *mode;
> +	struct v4l2_mbus_framefmt *fmt;
> +	struct v4l2_subdev_state *state;

> +	int vts;

Can be negative?

> +	int ret = 0;

How is this assignment useful?

> +	state = v4l2_subdev_get_locked_active_state(&ov2735->sd);
> +	fmt = v4l2_subdev_state_get_format(state, 0);
> +
> +	mode = v4l2_find_nearest_size(supported_modes,
> +				      ARRAY_SIZE(supported_modes),
> +				      width, height,
> +				      fmt->width, fmt->height);
> +
> +	if (ctrl->id == V4L2_CID_VBLANK) {
> +		/* Honour the VBLANK limits when setting exposure. */
> +		s64 max = mode->height + ctrl->val - 4;
> +
> +		ret = __v4l2_ctrl_modify_range(ov2735->exposure,
> +					       ov2735->exposure->minimum, max,
> +					 ov2735->exposure->step,
> +					 ov2735->exposure->default_value);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	/*
> +	 * Applying V4L2 control value only happens
> +	 * when power is up for streaming

Multi-line comments shouldn't neglect punctuation.

> +	 */
> +	if (pm_runtime_get_if_in_use(ov2735->dev) == 0)
> +		return 0;
> +
> +	ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
> +
> +	switch (ctrl->id) {
> +	case V4L2_CID_EXPOSURE:
> +		ret |= cci_write(ov2735->cci, OV2735_REG_LONG_EXPOSURE, ctrl->val, NULL);
> +		break;
> +	case V4L2_CID_ANALOGUE_GAIN:
> +		ret |= cci_write(ov2735->cci, OV2735_REG_ANALOG_GAIN, ctrl->val, NULL);
> +		break;
> +	case V4L2_CID_HBLANK:
> +		ret |= cci_write(ov2735->cci, OV2735_REG_HBLANK, ctrl->val, NULL);
> +		break;
> +	case V4L2_CID_VBLANK:
> +		vts = ctrl->val + mode->height;
> +		ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_EXP_SEPERATE_EN,
> +				 OV2735_FRAME_EXP_SEPERATE_EN, NULL);
> +		ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_LENGTH, vts, NULL);
> +		break;
> +	case V4L2_CID_TEST_PATTERN:
> +		ret = ov2735_enable_test_pattern(ov2735, ctrl->val);
> +		break;
> +	default:
> +		dev_err(ov2735->dev, "ctrl(id:0x%x, val:0x%x) is not handled\n",
> +			ctrl->id, ctrl->val);
> +		break;
> +	}
> +	ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_SYNC, 0x01, NULL);
> +
> +	pm_runtime_put(ov2735->dev);
> +
> +	return ret;
> +}

...

> +static int ov2735_init_controls(struct ov2735 *ov2735)
> +{
> +	struct v4l2_ctrl_handler *ctrl_hdlr;
> +	struct v4l2_fwnode_device_properties props;
> +	const struct ov2735_mode *mode = &supported_modes[0];
> +	u64 hblank_def, vblank_def, exp_max;
> +	int ret;
> +
> +	ctrl_hdlr = &ov2735->handler;
> +	ret = v4l2_ctrl_handler_init(ctrl_hdlr, 7);
> +	if (ret)
> +		return ret;
> +
> +	ov2735->pixel_rate = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops, V4L2_CID_PIXEL_RATE,
> +					       0, OV2735_PIXEL_RATE, 1, OV2735_PIXEL_RATE); 

Besides it's too long, it has trailing space.

> +
> +	ov2735->link_freq = v4l2_ctrl_new_int_menu(ctrl_hdlr, &ov2735_ctrl_ops,
> +						   V4L2_CID_LINK_FREQ,
> +						   0, 0, link_freq_menu_items);
> +	if (ov2735->link_freq)
> +		ov2735->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> +
> +	hblank_def =  mode->hts_def - mode->width;
> +	ov2735->hblank = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops, V4L2_CID_HBLANK,
> +					   hblank_def, hblank_def, 1, hblank_def);
> +
> +	vblank_def = mode->vts_def - mode->height;
> +	ov2735->vblank = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
> +					   V4L2_CID_VBLANK, vblank_def,
> +				OV2735_VTS_MAX - mode->height,
> +				1, vblank_def);

It's weird indentation.

> +
> +	exp_max = mode->vts_def - 4;
> +	ov2735->exposure = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
> +					     V4L2_CID_EXPOSURE, OV2735_EXPOSURE_MIN,
> +				exp_max, OV2735_EXPOSURE_STEP, mode->exp_def);
> +
> +	ov2735->gain = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
> +					 V4L2_CID_ANALOGUE_GAIN, ANALOG_GAIN_MIN,
> +				ANALOG_GAIN_MAX, ANALOG_GAIN_STEP,
> +				ANALOG_GAIN_DEFAULT);

Ditto.

> +	ov2735->test_pattern = v4l2_ctrl_new_std_menu_items(ctrl_hdlr,
> +							    &ov2735_ctrl_ops, V4L2_CID_TEST_PATTERN,
> +			ARRAY_SIZE(ov2735_test_pattern_menu) - 1,
> +			0, 0, ov2735_test_pattern_menu);

Ditto.

> +	if (ctrl_hdlr->error) {
> +		ret = ctrl_hdlr->error;
> +		dev_err(ov2735->dev, "control init failed (%d)\n", ret);
> +		goto error;
> +	}
> +
> +	ret = v4l2_fwnode_device_parse(ov2735->dev, &props);
> +	if (ret)
> +		goto error;
> +
> +	ret = v4l2_ctrl_new_fwnode_properties(ctrl_hdlr, &ov2735_ctrl_ops,
> +					      &props);
> +	if (ret)
> +		goto error;
> +
> +	ov2735->sd.ctrl_handler = ctrl_hdlr;
> +
> +	return 0;
> +error:

Usual way of naming labels is to explain what is going to  happen when goto.
Moreover it's even inconsistent, the below code use err prefix, but better
naming.

Here the

err_handler_free:

for example is better.

> +	v4l2_ctrl_handler_free(ctrl_hdlr);
> +
> +	return ret;
> +}

...

> +static int ov2735_enable_streams(struct v4l2_subdev *sd,
> +				 struct v4l2_subdev_state *state, u32 pad,
> +				u64 streams_mask)

Indentation issue.

> +{
> +	struct ov2735 *ov2735 = to_ov2735(sd);
> +	const struct ov2735_mode *mode;
> +	const struct ov2735_reglist *reg_list;
> +	const struct v4l2_mbus_framefmt *fmt;
> +	int ret = 0;

Needless assignment.

> +	fmt = v4l2_subdev_state_get_format(state, 0);
> +	mode = v4l2_find_nearest_size(supported_modes,
> +				      ARRAY_SIZE(supported_modes),
> +				      width, height,
> +				      fmt->width, fmt->height);
> +
> +	ret = pm_runtime_resume_and_get(ov2735->dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	reg_list = &mode->reg_list;
> +	ret = cci_multi_reg_write(ov2735->cci, reg_list->regvals, reg_list->num_regs, NULL);
> +	if (ret) {
> +		dev_err(ov2735->dev, "%s failed to send mfg header\n", __func__);
> +		goto err_rpm_put;
> +	}
> +
> +	/* Apply customized values from user */
> +	ret =  __v4l2_ctrl_handler_setup(ov2735->sd.ctrl_handler);
> +	if (ret)
> +		goto err_rpm_put;
> +
> +	/* set stream on register */
> +	ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
> +	ret |= cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_ON, NULL);
> +	if (ret)
> +		goto err_rpm_put;
> +
> +	return 0;
> +
> +err_rpm_put:
> +	pm_runtime_put(ov2735->dev);
> +	return ret;
> +}

...

> +static int ov2735_disable_streams(struct v4l2_subdev *sd,
> +				  struct v4l2_subdev_state *state, u32 pad,
> +				  u64 streams_mask)
> +{
> +	struct ov2735 *ov2735 = to_ov2735(sd);
> +	int ret = 0;
> +
> +	/* set stream off register */
> +	ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
> +	ret |= cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_OFF, NULL);

Why not using the ret parameter? Same for other similar cases above and beyond.

> +	if (ret)
> +		dev_err(ov2735->dev, "%s failed to set stream\n", __func__);
> +
> +	pm_runtime_put(ov2735->dev);
> +
> +	return ret;
> +}

...

> +static int ov2735_power_on(struct device *dev)
> +{
> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> +	struct ov2735 *ov2735 = to_ov2735(sd);

> +	int ret;
> +	unsigned long delay_us;

Why this order?

> +	gpiod_set_value_cansleep(ov2735->pwdn_gpio, 0);
> +	usleep_range(2000, 5000);

Use fsleep().

> +	ret = regulator_bulk_enable(ARRAY_SIZE(ov2735_supply_name),
> +				    ov2735->supplies);
> +	if (ret) {
> +		dev_err(ov2735->dev, "failed to enable regulators\n");
> +		return ret;
> +	}
> +
> +	gpiod_set_value_cansleep(ov2735->pwdn_gpio, 1);
> +	usleep_range(2000, 5000);

Ditto.

> +	gpiod_set_value_cansleep(ov2735->reset_gpio, 0);
> +	usleep_range(2000, 5000);

Ditto.

> +	ret = clk_prepare_enable(ov2735->xclk);
> +	if (ret) {
> +		dev_err(ov2735->dev, "failed to enable clock\n");
> +		goto regulator_off;
> +	}
> +
> +	/* 8192 cycles prior to first SCCB transaction */
> +	delay_us = DIV_ROUND_UP(8192, OV2735_XCLK_FREQ / 1000 / 1000);
> +	usleep_range(delay_us, delay_us * 2);

Ditto.

> +	return 0;
> +
> +regulator_off:

If you use 'err' prefix for error paths, here makes sense to continue.

> +	regulator_bulk_disable(ARRAY_SIZE(ov2735_supply_name), ov2735->supplies);
> +	return ret;
> +}

...

> +	struct v4l2_fwnode_endpoint bus_cfg = {
> +		.bus_type = V4L2_MBUS_CSI2_DPHY

Keep trailing comma.

> +	};

...

> +	ov2735 = devm_kzalloc(&client->dev, sizeof(*ov2735), GFP_KERNEL);

This requires device/devres.h.

> +	if (!ov2735)
> +		return -ENOMEM;

...

> +	ov2735->cci = devm_cci_regmap_init_i2c(client, 8);
> +	if (IS_ERR(ov2735->cci)) {
> +		ret = PTR_ERR(ov2735->cci);
> +		dev_err(ov2735->dev, "failed to initialize CCI: %d\n", ret);
> +		return ret;

Why not dev_err_probe()?

The code is full of inconsistency, please make sure it's one style.

> +	}

...

> +static DEFINE_RUNTIME_DEV_PM_OPS(ov2735_pm_ops, ov2735_power_off,
> +				 ov2735_power_on, NULL);

Make the logical split:

static DEFINE_RUNTIME_DEV_PM_OPS(ov2735_pm_ops,
				 ov2735_power_off, ov2735_power_on, NULL);

...

> +static struct i2c_driver ov2735_driver = {
> +	.driver = {
> +		.name = "ov2735",
> +		.pm = pm_ptr(&ov2735_pm_ops),
> +		.of_match_table = ov2735_id,

> +

Stray.

> +	},
> +	.probe = ov2735_probe,
> +	.remove = ov2735_remove,
> +};

> +

Unneeded.

> +module_i2c_driver(ov2735_driver);

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 2/2] media: i2c: add ov2735 image sensor driver

[Hardevsinh Palaniya]

Hi Andy,

Thanks for the review.

I have corrected the code, and all of your comments have now been addressed.

However, I have a question about one of the comments. Please see below. 

> On Mon, Jul 07, 2025 at 08:31:06PM +0530, Hardevsinh Palaniya wrote:
> > Add a v4l2 subdevice driver for the Omnivision OV2735 sensor.
> >
> > The Omnivision OV2735 is a 1/2.7-Inch CMOS image sensor with an
> > active array size of 1920 x 1080.
> >
> > - Manual exposure an gain control support
> > - vblank/hblank control support
> > - Supported resolution: 1920 x 1080 @ 30fps (SGRBG10)
> 
> ...
> 
> > +#include <linux/clk.h>
> > +#include <linux/delay.h>
> > +#include <linux/i2c.h>
> > +#include <linux/module.h>
> > +#include <linux/pm_runtime.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/units.h>
> 
> More stuff is in use than just these headers provide.
> E.g.,
> 
> + array_size.h
> + container_of.h
> + gpio/consumer.h
> + types.h
> 
> And so on... Also in some cases the forward declarations are enough to have.
> 
> .,,
> 
> > +#define OV2735_LINK_FREQ_420MHZ                      420000000
> 
> HZ_PER_MHZ ?
> 
> ...
> 
> > +#define OV2735_PIXEL_RATE                    168000000
> 
> What's the unit?
> 
> ...
> 
> > +static const s64 link_freq_menu_items[] = {
> > +     OV2735_LINK_FREQ_420MHZ
> 
> Keep the trailing comma like you have done in other cases.
> 
> > +};
> 
> ...
> 
> > +static int ov2735_enable_test_pattern(struct ov2735 *ov2735, u32 pattern)
> > +{
> > +     int ret;
> > +     u64 val;
> > +
> > +     ret = cci_read(ov2735->cci, OV2735_REG_TEST_PATTERN, &val, NULL);
> > +     if (ret)
> > +             return ret;
> > +
> > +     switch (pattern) {
> > +     case 0:
> > +             val &= ~OV2735_TEST_PATTERN_ENABLE;
> > +             break;
> > +     case 1:
> > +             val |= OV2735_TEST_PATTERN_ENABLE;
> > +             break;
> > +     }
> 
> > +     ret = cci_write(ov2735->cci, OV2735_REG_TEST_PATTERN, val, NULL);
> > +     if (ret)
> > +             return ret;
> > +
> > +     return 0;
> 
> Is this the required style? Because these 5 LoCs is just a simple
> 
>         return cci_write(ov2735->cci, OV2735_REG_TEST_PATTERN, val, NULL);
> 
> > +}
> 
> ...
> 
> > +static int ov2735_set_ctrl(struct v4l2_ctrl *ctrl)
> > +{
> > +     struct ov2735 *ov2735 = container_of(ctrl->handler, struct ov2735,
> > +                                          handler);
> > +     const struct ov2735_mode *mode;
> > +     struct v4l2_mbus_framefmt *fmt;
> > +     struct v4l2_subdev_state *state;
> 
> > +     int vts;
> 
> Can be negative?
> 
> > +     int ret = 0;
> 
> How is this assignment useful?
> 
> > +     state = v4l2_subdev_get_locked_active_state(&ov2735->sd);
> > +     fmt = v4l2_subdev_state_get_format(state, 0);
> > +
> > +     mode = v4l2_find_nearest_size(supported_modes,
> > +                                   ARRAY_SIZE(supported_modes),
> > +                                   width, height,
> > +                                   fmt->width, fmt->height);
> > +
> > +     if (ctrl->id == V4L2_CID_VBLANK) {
> > +             /* Honour the VBLANK limits when setting exposure. */
> > +             s64 max = mode->height + ctrl->val - 4;
> > +
> > +             ret = __v4l2_ctrl_modify_range(ov2735->exposure,
> > +                                            ov2735->exposure->minimum, max,
> > +                                      ov2735->exposure->step,
> > +                                      ov2735->exposure->default_value);
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +
> > +     /*
> > +      * Applying V4L2 control value only happens
> > +      * when power is up for streaming
> 
> Multi-line comments shouldn't neglect punctuation.
> 
> > +      */
> > +     if (pm_runtime_get_if_in_use(ov2735->dev) == 0)
> > +             return 0;
> > +
> > +     ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
> > +
> > +     switch (ctrl->id) {
> > +     case V4L2_CID_EXPOSURE:
> > +             ret |= cci_write(ov2735->cci, OV2735_REG_LONG_EXPOSURE, ctrl->val, NULL);
> > +             break;
> > +     case V4L2_CID_ANALOGUE_GAIN:
> > +             ret |= cci_write(ov2735->cci, OV2735_REG_ANALOG_GAIN, ctrl->val, NULL);
> > +             break;
> > +     case V4L2_CID_HBLANK:
> > +             ret |= cci_write(ov2735->cci, OV2735_REG_HBLANK, ctrl->val, NULL);
> > +             break;
> > +     case V4L2_CID_VBLANK:
> > +             vts = ctrl->val + mode->height;
> > +             ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_EXP_SEPERATE_EN,
> > +                              OV2735_FRAME_EXP_SEPERATE_EN, NULL);
> > +             ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_LENGTH, vts, NULL);
> > +             break;
> > +     case V4L2_CID_TEST_PATTERN:
> > +             ret = ov2735_enable_test_pattern(ov2735, ctrl->val);
> > +             break;
> > +     default:
> > +             dev_err(ov2735->dev, "ctrl(id:0x%x, val:0x%x) is not handled\n",
> > +                     ctrl->id, ctrl->val);
> > +             break;
> > +     }
> > +     ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_SYNC, 0x01, NULL);
> > +
> > +     pm_runtime_put(ov2735->dev);
> > +
> > +     return ret;
> > +}
> 
> ...
> 
> > +static int ov2735_init_controls(struct ov2735 *ov2735)
> > +{
> > +     struct v4l2_ctrl_handler *ctrl_hdlr;
> > +     struct v4l2_fwnode_device_properties props;
> > +     const struct ov2735_mode *mode = &supported_modes[0];
> > +     u64 hblank_def, vblank_def, exp_max;
> > +     int ret;
> > +
> > +     ctrl_hdlr = &ov2735->handler;
> > +     ret = v4l2_ctrl_handler_init(ctrl_hdlr, 7);
> > +     if (ret)
> > +             return ret;
> > +
> > +     ov2735->pixel_rate = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops, V4L2_CID_PIXEL_RATE,
> > +                                            0, OV2735_PIXEL_RATE, 1, OV2735_PIXEL_RATE);
> 
> Besides it's too long, it has trailing space.
> 
> > +
> > +     ov2735->link_freq = v4l2_ctrl_new_int_menu(ctrl_hdlr, &ov2735_ctrl_ops,
> > +                                                V4L2_CID_LINK_FREQ,
> > +                                                0, 0, link_freq_menu_items);
> > +     if (ov2735->link_freq)
> > +             ov2735->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> > +
> > +     hblank_def =  mode->hts_def - mode->width;
> > +     ov2735->hblank = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops, V4L2_CID_HBLANK,
> > +                                        hblank_def, hblank_def, 1, hblank_def);
> > +
> > +     vblank_def = mode->vts_def - mode->height;
> > +     ov2735->vblank = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
> > +                                        V4L2_CID_VBLANK, vblank_def,
> > +                             OV2735_VTS_MAX - mode->height,
> > +                             1, vblank_def);
> 
> It's weird indentation.
> 
> > +
> > +     exp_max = mode->vts_def - 4;
> > +     ov2735->exposure = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
> > +                                          V4L2_CID_EXPOSURE, OV2735_EXPOSURE_MIN,
> > +                             exp_max, OV2735_EXPOSURE_STEP, mode->exp_def);
> > +
> > +     ov2735->gain = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
> > +                                      V4L2_CID_ANALOGUE_GAIN, ANALOG_GAIN_MIN,
> > +                             ANALOG_GAIN_MAX, ANALOG_GAIN_STEP,
> > +                             ANALOG_GAIN_DEFAULT);
> 
> Ditto.
> 
> > +     ov2735->test_pattern = v4l2_ctrl_new_std_menu_items(ctrl_hdlr,
> > +                                                         &ov2735_ctrl_ops, V4L2_CID_TEST_PATTERN,
> > +                     ARRAY_SIZE(ov2735_test_pattern_menu) - 1,
> > +                     0, 0, ov2735_test_pattern_menu);
> 
> Ditto.
> 
> > +     if (ctrl_hdlr->error) {
> > +             ret = ctrl_hdlr->error;
> > +             dev_err(ov2735->dev, "control init failed (%d)\n", ret);
> > +             goto error;
> > +     }
> > +
> > +     ret = v4l2_fwnode_device_parse(ov2735->dev, &props);
> > +     if (ret)
> > +             goto error;
> > +
> > +     ret = v4l2_ctrl_new_fwnode_properties(ctrl_hdlr, &ov2735_ctrl_ops,
> > +                                           &props);
> > +     if (ret)
> > +             goto error;
> > +
> > +     ov2735->sd.ctrl_handler = ctrl_hdlr;
> > +
> > +     return 0;
> > +error:
> 
> Usual way of naming labels is to explain what is going to  happen when goto.
> Moreover it's even inconsistent, the below code use err prefix, but better
> naming.
> 
> Here the
> 
> err_handler_free:
> 
> for example is better.
> 
> > +     v4l2_ctrl_handler_free(ctrl_hdlr);
> > +
> > +     return ret;
> > +}
> 
> ...
> 
> > +static int ov2735_enable_streams(struct v4l2_subdev *sd,
> > +                              struct v4l2_subdev_state *state, u32 pad,
> > +                             u64 streams_mask)
> 
> Indentation issue.
> 
> > +{
> > +     struct ov2735 *ov2735 = to_ov2735(sd);
> > +     const struct ov2735_mode *mode;
> > +     const struct ov2735_reglist *reg_list;
> > +     const struct v4l2_mbus_framefmt *fmt;
> > +     int ret = 0;
> 
> Needless assignment.
> 
> > +     fmt = v4l2_subdev_state_get_format(state, 0);
> > +     mode = v4l2_find_nearest_size(supported_modes,
> > +                                   ARRAY_SIZE(supported_modes),
> > +                                   width, height,
> > +                                   fmt->width, fmt->height);
> > +
> > +     ret = pm_runtime_resume_and_get(ov2735->dev);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     reg_list = &mode->reg_list;
> > +     ret = cci_multi_reg_write(ov2735->cci, reg_list->regvals, reg_list->num_regs, NULL);
> > +     if (ret) {
> > +             dev_err(ov2735->dev, "%s failed to send mfg header\n", __func__);
> > +             goto err_rpm_put;
> > +     }
> > +
> > +     /* Apply customized values from user */
> > +     ret =  __v4l2_ctrl_handler_setup(ov2735->sd.ctrl_handler);
> > +     if (ret)
> > +             goto err_rpm_put;
> > +
> > +     /* set stream on register */
> > +     ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
> > +     ret |= cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_ON, NULL);
> > +     if (ret)
> > +             goto err_rpm_put;
> > +
> > +     return 0;
> > +
> > +err_rpm_put:
> > +     pm_runtime_put(ov2735->dev);
> > +     return ret;
> > +}
> 
> ...
> 
> > +static int ov2735_disable_streams(struct v4l2_subdev *sd,
> > +                               struct v4l2_subdev_state *state, u32 pad,
> > +                               u64 streams_mask)
> > +{
> > +     struct ov2735 *ov2735 = to_ov2735(sd);
> > +     int ret = 0;
> > +
> > +     /* set stream off register */
> > +     ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
> > +     ret |= cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_OFF, NULL);
> 
> Why not using the ret parameter? Same for other similar cases above and beyond.

I am not sure what you want to suggest here.

Do I need to check ret like this?

ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
if (ret) {
    // error message
}

ret = cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_OFF, NULL);
if (ret) {
    // error message
}

Best Regards,
Hardev

Re: [PATCH 2/2] media: i2c: add ov2735 image sensor driver

[Yan, Dongcheng]

Hi Hardevsinh,

On 7/8/2025 3:04 PM, Hardevsinh Palaniya wrote:
> Hi Andy,
> 
> Thanks for the review.
> 
> I have corrected the code, and all of your comments have now been addressed.
> 
> However, I have a question about one of the comments. Please see below. 
> 
>> On Mon, Jul 07, 2025 at 08:31:06PM +0530, Hardevsinh Palaniya wrote:
>>> Add a v4l2 subdevice driver for the Omnivision OV2735 sensor.
>>>
>>> The Omnivision OV2735 is a 1/2.7-Inch CMOS image sensor with an
>>> active array size of 1920 x 1080.
>>>
>>> - Manual exposure an gain control support
>>> - vblank/hblank control support
>>> - Supported resolution: 1920 x 1080 @ 30fps (SGRBG10)
>>
>> ...
>>
>>> +#include <linux/clk.h>
>>> +#include <linux/delay.h>
>>> +#include <linux/i2c.h>
>>> +#include <linux/module.h>
>>> +#include <linux/pm_runtime.h>
>>> +#include <linux/regulator/consumer.h>
>>> +#include <linux/units.h>
>>
>> More stuff is in use than just these headers provide.
>> E.g.,
>>
>> + array_size.h
>> + container_of.h
>> + gpio/consumer.h
>> + types.h
>>
>> And so on... Also in some cases the forward declarations are enough to have.
>>
>> .,,
>>
>>> +#define OV2735_LINK_FREQ_420MHZ                      420000000
>>
>> HZ_PER_MHZ ?
>>
>> ...
>>
>>> +#define OV2735_PIXEL_RATE                    168000000
>>
>> What's the unit?
>>
>> ...
>>
>>> +static const s64 link_freq_menu_items[] = {
>>> +     OV2735_LINK_FREQ_420MHZ
>>
>> Keep the trailing comma like you have done in other cases.
>>
>>> +};
>>
>> ...
>>
>>> +static int ov2735_enable_test_pattern(struct ov2735 *ov2735, u32 pattern)
>>> +{
>>> +     int ret;
>>> +     u64 val;
>>> +
>>> +     ret = cci_read(ov2735->cci, OV2735_REG_TEST_PATTERN, &val, NULL);
>>> +     if (ret)
>>> +             return ret;
>>> +
>>> +     switch (pattern) {
>>> +     case 0:
>>> +             val &= ~OV2735_TEST_PATTERN_ENABLE;
>>> +             break;
>>> +     case 1:
>>> +             val |= OV2735_TEST_PATTERN_ENABLE;
>>> +             break;
>>> +     }
>>
>>> +     ret = cci_write(ov2735->cci, OV2735_REG_TEST_PATTERN, val, NULL);
>>> +     if (ret)
>>> +             return ret;
>>> +
>>> +     return 0;
>>
>> Is this the required style? Because these 5 LoCs is just a simple
>>
>>         return cci_write(ov2735->cci, OV2735_REG_TEST_PATTERN, val, NULL);
>>
>>> +}
>>
>> ...
>>
>>> +static int ov2735_set_ctrl(struct v4l2_ctrl *ctrl)
>>> +{
>>> +     struct ov2735 *ov2735 = container_of(ctrl->handler, struct ov2735,
>>> +                                          handler);
>>> +     const struct ov2735_mode *mode;
>>> +     struct v4l2_mbus_framefmt *fmt;
>>> +     struct v4l2_subdev_state *state;
>>
>>> +     int vts;
>>
>> Can be negative?
>>
>>> +     int ret = 0;
>>
>> How is this assignment useful?
>>
>>> +     state = v4l2_subdev_get_locked_active_state(&ov2735->sd);
>>> +     fmt = v4l2_subdev_state_get_format(state, 0);
>>> +
>>> +     mode = v4l2_find_nearest_size(supported_modes,
>>> +                                   ARRAY_SIZE(supported_modes),
>>> +                                   width, height,
>>> +                                   fmt->width, fmt->height);
>>> +
>>> +     if (ctrl->id == V4L2_CID_VBLANK) {
>>> +             /* Honour the VBLANK limits when setting exposure. */
>>> +             s64 max = mode->height + ctrl->val - 4;
>>> +
>>> +             ret = __v4l2_ctrl_modify_range(ov2735->exposure,
>>> +                                            ov2735->exposure->minimum, max,
>>> +                                      ov2735->exposure->step,
>>> +                                      ov2735->exposure->default_value);
>>> +             if (ret)
>>> +                     return ret;
>>> +     }
>>> +
>>> +     /*
>>> +      * Applying V4L2 control value only happens
>>> +      * when power is up for streaming
>>
>> Multi-line comments shouldn't neglect punctuation.
>>
>>> +      */
>>> +     if (pm_runtime_get_if_in_use(ov2735->dev) == 0)
>>> +             return 0;
>>> +
>>> +     ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
>>> +
>>> +     switch (ctrl->id) {
>>> +     case V4L2_CID_EXPOSURE:
>>> +             ret |= cci_write(ov2735->cci, OV2735_REG_LONG_EXPOSURE, ctrl->val, NULL);
>>> +             break;
>>> +     case V4L2_CID_ANALOGUE_GAIN:
>>> +             ret |= cci_write(ov2735->cci, OV2735_REG_ANALOG_GAIN, ctrl->val, NULL);
>>> +             break;
>>> +     case V4L2_CID_HBLANK:
>>> +             ret |= cci_write(ov2735->cci, OV2735_REG_HBLANK, ctrl->val, NULL);
>>> +             break;
>>> +     case V4L2_CID_VBLANK:
>>> +             vts = ctrl->val + mode->height;
>>> +             ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_EXP_SEPERATE_EN,
>>> +                              OV2735_FRAME_EXP_SEPERATE_EN, NULL);
>>> +             ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_LENGTH, vts, NULL);
>>> +             break;
>>> +     case V4L2_CID_TEST_PATTERN:
>>> +             ret = ov2735_enable_test_pattern(ov2735, ctrl->val);
>>> +             break;
>>> +     default:
>>> +             dev_err(ov2735->dev, "ctrl(id:0x%x, val:0x%x) is not handled\n",
>>> +                     ctrl->id, ctrl->val);
>>> +             break;
>>> +     }
>>> +     ret |= cci_write(ov2735->cci, OV2735_REG_FRAME_SYNC, 0x01, NULL);
>>> +
>>> +     pm_runtime_put(ov2735->dev);
>>> +
>>> +     return ret;
>>> +}
>>
>> ...
>>
>>> +static int ov2735_init_controls(struct ov2735 *ov2735)
>>> +{
>>> +     struct v4l2_ctrl_handler *ctrl_hdlr;
>>> +     struct v4l2_fwnode_device_properties props;
>>> +     const struct ov2735_mode *mode = &supported_modes[0];
>>> +     u64 hblank_def, vblank_def, exp_max;
>>> +     int ret;
>>> +
>>> +     ctrl_hdlr = &ov2735->handler;
>>> +     ret = v4l2_ctrl_handler_init(ctrl_hdlr, 7);
>>> +     if (ret)
>>> +             return ret;
>>> +
>>> +     ov2735->pixel_rate = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops, V4L2_CID_PIXEL_RATE,
>>> +                                            0, OV2735_PIXEL_RATE, 1, OV2735_PIXEL_RATE);
>>
>> Besides it's too long, it has trailing space.
>>
>>> +
>>> +     ov2735->link_freq = v4l2_ctrl_new_int_menu(ctrl_hdlr, &ov2735_ctrl_ops,
>>> +                                                V4L2_CID_LINK_FREQ,
>>> +                                                0, 0, link_freq_menu_items);
>>> +     if (ov2735->link_freq)
>>> +             ov2735->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
>>> +
>>> +     hblank_def =  mode->hts_def - mode->width;
>>> +     ov2735->hblank = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops, V4L2_CID_HBLANK,
>>> +                                        hblank_def, hblank_def, 1, hblank_def);
>>> +
>>> +     vblank_def = mode->vts_def - mode->height;
>>> +     ov2735->vblank = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
>>> +                                        V4L2_CID_VBLANK, vblank_def,
>>> +                             OV2735_VTS_MAX - mode->height,
>>> +                             1, vblank_def);
>>
>> It's weird indentation.
>>
>>> +
>>> +     exp_max = mode->vts_def - 4;
>>> +     ov2735->exposure = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
>>> +                                          V4L2_CID_EXPOSURE, OV2735_EXPOSURE_MIN,
>>> +                             exp_max, OV2735_EXPOSURE_STEP, mode->exp_def);
>>> +
>>> +     ov2735->gain = v4l2_ctrl_new_std(ctrl_hdlr, &ov2735_ctrl_ops,
>>> +                                      V4L2_CID_ANALOGUE_GAIN, ANALOG_GAIN_MIN,
>>> +                             ANALOG_GAIN_MAX, ANALOG_GAIN_STEP,
>>> +                             ANALOG_GAIN_DEFAULT);
>>
>> Ditto.
>>
>>> +     ov2735->test_pattern = v4l2_ctrl_new_std_menu_items(ctrl_hdlr,
>>> +                                                         &ov2735_ctrl_ops, V4L2_CID_TEST_PATTERN,
>>> +                     ARRAY_SIZE(ov2735_test_pattern_menu) - 1,
>>> +                     0, 0, ov2735_test_pattern_menu);
>>
>> Ditto.
>>
>>> +     if (ctrl_hdlr->error) {
>>> +             ret = ctrl_hdlr->error;
>>> +             dev_err(ov2735->dev, "control init failed (%d)\n", ret);
>>> +             goto error;
>>> +     }
>>> +
>>> +     ret = v4l2_fwnode_device_parse(ov2735->dev, &props);
>>> +     if (ret)
>>> +             goto error;
>>> +
>>> +     ret = v4l2_ctrl_new_fwnode_properties(ctrl_hdlr, &ov2735_ctrl_ops,
>>> +                                           &props);
>>> +     if (ret)
>>> +             goto error;
>>> +
>>> +     ov2735->sd.ctrl_handler = ctrl_hdlr;
>>> +
>>> +     return 0;
>>> +error:
>>
>> Usual way of naming labels is to explain what is going to  happen when goto.
>> Moreover it's even inconsistent, the below code use err prefix, but better
>> naming.
>>
>> Here the
>>
>> err_handler_free:
>>
>> for example is better.
>>
>>> +     v4l2_ctrl_handler_free(ctrl_hdlr);
>>> +
>>> +     return ret;
>>> +}
>>
>> ...
>>
>>> +static int ov2735_enable_streams(struct v4l2_subdev *sd,
>>> +                              struct v4l2_subdev_state *state, u32 pad,
>>> +                             u64 streams_mask)
>>
>> Indentation issue.
>>
>>> +{
>>> +     struct ov2735 *ov2735 = to_ov2735(sd);
>>> +     const struct ov2735_mode *mode;
>>> +     const struct ov2735_reglist *reg_list;
>>> +     const struct v4l2_mbus_framefmt *fmt;
>>> +     int ret = 0;
>>
>> Needless assignment.
>>
>>> +     fmt = v4l2_subdev_state_get_format(state, 0);
>>> +     mode = v4l2_find_nearest_size(supported_modes,
>>> +                                   ARRAY_SIZE(supported_modes),
>>> +                                   width, height,
>>> +                                   fmt->width, fmt->height);
>>> +
>>> +     ret = pm_runtime_resume_and_get(ov2735->dev);
>>> +     if (ret < 0)
>>> +             return ret;
>>> +
>>> +     reg_list = &mode->reg_list;
>>> +     ret = cci_multi_reg_write(ov2735->cci, reg_list->regvals, reg_list->num_regs, NULL);
>>> +     if (ret) {
>>> +             dev_err(ov2735->dev, "%s failed to send mfg header\n", __func__);
>>> +             goto err_rpm_put;
>>> +     }
>>> +
>>> +     /* Apply customized values from user */
>>> +     ret =  __v4l2_ctrl_handler_setup(ov2735->sd.ctrl_handler);
>>> +     if (ret)
>>> +             goto err_rpm_put;
>>> +
>>> +     /* set stream on register */
>>> +     ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
>>> +     ret |= cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_ON, NULL);
>>> +     if (ret)
>>> +             goto err_rpm_put;
>>> +
>>> +     return 0;
>>> +
>>> +err_rpm_put:
>>> +     pm_runtime_put(ov2735->dev);
>>> +     return ret;
>>> +}
>>
>> ...
>>
>>> +static int ov2735_disable_streams(struct v4l2_subdev *sd,
>>> +                               struct v4l2_subdev_state *state, u32 pad,
>>> +                               u64 streams_mask)
>>> +{
>>> +     struct ov2735 *ov2735 = to_ov2735(sd);
>>> +     int ret = 0;
>>> +
>>> +     /* set stream off register */
>>> +     ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
>>> +     ret |= cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_OFF, NULL);
>>
>> Why not using the ret parameter? Same for other similar cases above and beyond.
> 
> I am not sure what you want to suggest here.
> 
> Do I need to check ret like this?
> 
> ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
> if (ret) {
>     // error message
> }
> 
> ret = cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_OFF, NULL);
> if (ret) {
>     // error message
> }
> 

cci_write/read has a param named ret, for example:
cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, &ret);
cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_OFF, &ret);
then check ret here or return ret.

Thanks,
Dongcheng> Best Regards,
> Hardev

Re: [PATCH 2/2] media: i2c: add ov2735 image sensor driver

[Andy Shevchenko]

On Tue, Jul 08, 2025 at 07:04:48AM +0000, Hardevsinh Palaniya wrote:
> > On Mon, Jul 07, 2025 at 08:31:06PM +0530, Hardevsinh Palaniya wrote:

...

> > > +static int ov2735_disable_streams(struct v4l2_subdev *sd,
> > > +                               struct v4l2_subdev_state *state, u32 pad,
> > > +                               u64 streams_mask)
> > > +{
> > > +     struct ov2735 *ov2735 = to_ov2735(sd);
> > > +     int ret = 0;
> > > +
> > > +     /* set stream off register */
> > > +     ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
> > > +     ret |= cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_OFF, NULL);
> > 
> > Why not using the ret parameter? Same for other similar cases above and beyond.
> 
> I am not sure what you want to suggest here.
> 
> Do I need to check ret like this?
> 
> ret = cci_write(ov2735->cci, OV2735_REG_PAGE_SELECT, 0x01, NULL);
> if (ret) {
>     // error message
> }
> 
> ret = cci_write(ov2735->cci, OV2735_REG_STREAM_CTRL, OV2735_STREAM_OFF, NULL);
> if (ret) {
>     // error message
> }

No, this is the idea behind it, you check only when you need it.

-- 
With Best Regards,
Andy Shevchenko