[PATCH v5 0/6] drm/ssd130x: Add support for the Solomon SSD1351 OLED controller

[PATCH v5 0/6] drm/ssd130x: Add support for the Solomon SSD1351 OLED controller

[Amit Barzilai]

This series adds support for the Solomon SSD1351, a 128x128 65k-color
RGB OLED controller, to the ssd130x DRM driver:

  - Patch 1 adds the device tree binding.

  - Patch 2 switches the SSD133X family from RGB332 to RGB565, bringing
    65k color to the SSD1331.

  - Patches 3 to 5 are preparatory cleanups requested on v3: constify
    the ssd130x_write_data() 'values' parameter, convert
    ssd130x_spi_id[] to C99 initializers, and reimplement
    ssd130x_write_cmd() as a variadic wrapper around
    ssd130x_write_cmds() so a single loop remains.

  - Patch 6 adds the SSD1351 as a new SSD135X_FAMILY. It gets its own
    primary plane update/disable, encoder enable and backlight
    callbacks; only the callbacks with no family-specific logic
    (ssd133x_primary_plane_atomic_check(), ssd133x_crtc_atomic_check()
    and ssd130x_encoder_atomic_disable()) are reused as is. It also
    sends command parameters on the data path, handled in
    ssd130x_write_cmds() via a new cmd_params_are_data flag; see [2]
    for why the split lives there rather than in the SPI transport.

Testing:

  - Patches 1, 3, 4, 5 and 6 are tested on an SSD1351.
  - The SSD1331 RGB565 change (patch 2) was kindly tested by Javier on
    his SSD1331.

Thanks to Javier, Andy, Krzysztof and Fabio for the reviews.

[1] v4 of this series:
    https://lore.kernel.org/dri-devel/20260818080626.30430-1-amit.barzilai22@gmail.com
[2] Command parameter path discussion:
    https://lore.kernel.org/dri-devel/20260811122603.30773-1-amit.barzilai22@gmail.com

---

Changes since v4:
- Move assignment of fi and plane_state to be just before their
  first use.
- Move ret variable declaration below cmds[] in ssd135x_init().
- Constify remap variable in ssd133x_init() and ssd135x_init().
- Replace ARRAY_SIZE() with sizeof() in ssd130x_write_cmd().
- Collect Andy's Reviewed-by tags on patches 3 and 4.

Amit Barzilai (6):
  dt-bindings: display: Add Solomon SSD1351 OLED controller
  drm/ssd130x: Change SSD133X color format to RGB565 from RGB332
  drm/ssd130x: Constify ssd130x_write_data() 'values' parameter
  drm/ssd130x: Replace positional ssd130x_spi_id[] initialization with
    C99
  drm/ssd130x: Implement ssd130x_write_cmd() on top of
    ssd130x_write_cmds()
  drm/ssd130x: Add SSD135X_FAMILY and SSD1351 support

 .../bindings/display/solomon,ssd1351.yaml     |  42 ++
 drivers/gpu/drm/solomon/ssd130x-spi.c         |  25 +-
 drivers/gpu/drm/solomon/ssd130x.c             | 420 +++++++++++++++---
 drivers/gpu/drm/solomon/ssd130x.h             |  10 +-
 4 files changed, 432 insertions(+), 65 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/display/solomon,ssd1351.yaml


base-commit: 843bc34db94bff0612c8294861b156489958897b
-- 
2.55.0

[PATCH v5 1/6] dt-bindings: display: Add Solomon SSD1351 OLED controller

[Amit Barzilai]

Add a device tree binding for the Solomon SSD1351, a 128x128 65k-color
RGB OLED display controller driven over a 4-wire SPI bus. The binding
builds on the shared solomon,ssd-common.yaml properties already used by
the other Solomon display controllers.

Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Amit Barzilai <amit.barzilai22@gmail.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
---
 .../bindings/display/solomon,ssd1351.yaml     | 42 +++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/solomon,ssd1351.yaml

diff --git a/Documentation/devicetree/bindings/display/solomon,ssd1351.yaml b/Documentation/devicetree/bindings/display/solomon,ssd1351.yaml
new file mode 100644
index 000000000000..80850c2ab5b3
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/solomon,ssd1351.yaml
@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/solomon,ssd1351.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Solomon SSD1351 OLED Display Controller
+
+maintainers:
+  - Amit Barzilai <amit.barzilai22@gmail.com>
+  - Javier Martinez Canillas <javierm@redhat.com>
+
+allOf:
+  - $ref: solomon,ssd-common.yaml#
+
+properties:
+  compatible:
+    enum:
+      - solomon,ssd1351
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        oled@0 {
+            compatible = "solomon,ssd1351";
+            reg = <0x0>;
+            reset-gpios = <&gpio2 7 GPIO_ACTIVE_LOW>;
+            dc-gpios = <&gpio2 8 GPIO_ACTIVE_HIGH>;
+            spi-max-frequency = <10000000>;
+        };
+    };
-- 
2.55.0

[PATCH v5 2/6] drm/ssd130x: Change SSD133X color format to RGB565 from RGB332

[Amit Barzilai]

SSD133X screens were driven at 8bpp RGB332 despite supporting 16bpp RGB565.
Switch the SSD133X data path to RGB565.

Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Amit Barzilai <amit.barzilai22@gmail.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
---
 drivers/gpu/drm/solomon/ssd130x.c | 48 ++++++++++++++++++++-----------
 1 file changed, 31 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index 0b0fc6fe3df2..8cf1e9c84a81 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -146,6 +146,11 @@
 #define SSD133X_DEFAULT_CONTRAST_B		0x50
 #define SSD133X_DEFAULT_CONTRAST_C		0x7d
 
+/* ssd133x remap byte (data of SSD13XX_SET_SEG_REMAP) */
+#define SSD133X_SET_REMAP_COM_SPLIT		BIT(5)
+#define SSD133X_SET_REMAP_COLOR_DEPTH_MASK	GENMASK(7, 6)
+#define SSD133X_COLOR_DEPTH_65K			0x1
+
 #define MAX_CONTRAST 255
 
 const struct ssd130x_deviceinfo ssd130x_variants[] = {
@@ -618,17 +623,17 @@ static int ssd133x_set_contrast(struct ssd130x_device *ssd130x, u32 brightness)
 static int ssd133x_init(struct ssd130x_device *ssd130x)
 {
 	int ret;
+	/*
+	 * Horizontal address increment, normal SA,SB,SC (e.g. RGB) sub-pixel
+	 * order, COM split odd even and 65k (RGB565) color depth.
+	 */
+	const u8 remap = SSD133X_SET_REMAP_COM_SPLIT |
+			 FIELD_PREP(SSD133X_SET_REMAP_COLOR_DEPTH_MASK, SSD133X_COLOR_DEPTH_65K);
 	const u8 cmds[] = {
 		2, SSD133X_SET_MASTER_CURRENT, 0x06,
 		3, SSD133X_SET_COL_RANGE, 0x00, ssd130x->width - 1,
 		3, SSD133X_SET_ROW_RANGE, 0x00, ssd130x->height - 1,
-		/*
-		 * Horizontal Address Increment
-		 * Normal order SA,SB,SC (e.g. RGB)
-		 * COM Split Odd Even
-		 * 256 color format
-		 */
-		2, SSD13XX_SET_SEG_REMAP, 0x20,
+		2, SSD13XX_SET_SEG_REMAP, remap,
 		2, SSD133X_SET_DISPLAY_START, 0x00,
 		2, SSD133X_SET_DISPLAY_OFFSET, 0x00,
 		1, SSD133X_SET_DISPLAY_NORMAL,
@@ -829,14 +834,20 @@ static int ssd133x_update_rect(struct ssd130x_device *ssd130x,
 	 * COM0 to COM[N - 1] are the rows and SEG0 to SEG[M - 1] are
 	 * the columns.
 	 *
-	 * Each Segment has a 8-bit pixel and each Common output has a
-	 * row of pixels. When using the (default) horizontal address
-	 * increment mode, each byte of data sent to the controller has
-	 * a Segment (e.g: SEG0).
+	 * Each Segment holds one pixel and each Common output has a row
+	 * of pixels. A pixel is 8 bits (one byte) in the 256 color
+	 * (RGB332) format or 16 bits (two bytes) in the 65k color
+	 * (RGB565) format. When using the (default) horizontal address
+	 * increment mode, the pixel data is sent Segment by Segment
+	 * (e.g: SEG0 first).
 	 *
 	 * When using the 256 color depth format, each pixel contains 3
-	 * sub-pixels for color A, B and C. These have 3 bit, 3 bit and
-	 * 2 bits respectively.
+	 * sub-pixels for color A, B and C. These have 3, 3 and 2 bits
+	 * respectively.
+	 *
+	 * When using the 65k color depth format, each pixel contains 3
+	 * sub-pixels for color A, B and C. These have 5, 6 and 5 bits
+	 * respectively.
 	 */
 
 	/* Set column start and end */
@@ -909,9 +920,10 @@ static void ssd132x_clear_screen(struct ssd130x_device *ssd130x, u8 *data_array)
 
 static void ssd133x_clear_screen(struct ssd130x_device *ssd130x, u8 *data_array)
 {
-	const struct drm_format_info *fi = drm_format_info(DRM_FORMAT_RGB332);
+	const struct drm_format_info *fi;
 	unsigned int pitch;
 
+	fi = drm_format_info(DRM_FORMAT_RGB565);
 	if (!fi)
 		return;
 
@@ -978,17 +990,18 @@ static int ssd133x_fb_blit_rect(struct drm_framebuffer *fb,
 				struct drm_format_conv_state *fmtcnv_state)
 {
 	struct ssd130x_device *ssd130x = drm_to_ssd130x(fb->dev);
-	const struct drm_format_info *fi = drm_format_info(DRM_FORMAT_RGB332);
+	const struct drm_format_info *fi;
 	unsigned int dst_pitch;
 	struct iosys_map dst;
 
+	fi = drm_format_info(DRM_FORMAT_RGB565);
 	if (!fi)
 		return -EINVAL;
 
 	dst_pitch = drm_format_info_min_pitch(fi, 0, drm_rect_width(rect));
 
 	iosys_map_set_vaddr(&dst, data_array);
-	drm_fb_xrgb8888_to_rgb332(&dst, &dst_pitch, vmap, fb, rect, fmtcnv_state);
+	drm_fb_xrgb8888_to_rgb565be(&dst, &dst_pitch, vmap, fb, rect, fmtcnv_state);
 
 	ssd133x_update_rect(ssd130x, rect, data_array, dst_pitch);
 
@@ -1446,10 +1459,11 @@ static int ssd133x_crtc_atomic_check(struct drm_crtc *crtc,
 	struct ssd130x_device *ssd130x = drm_to_ssd130x(drm);
 	struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
 	struct ssd130x_crtc_state *ssd130x_state = to_ssd130x_crtc_state(crtc_state);
-	const struct drm_format_info *fi = drm_format_info(DRM_FORMAT_RGB332);
+	const struct drm_format_info *fi;
 	unsigned int pitch;
 	int ret;
 
+	fi = drm_format_info(DRM_FORMAT_RGB565);
 	if (!fi)
 		return -EINVAL;
 
-- 
2.55.0

[PATCH v5 3/6] drm/ssd130x: Constify ssd130x_write_data() 'values' parameter

[Amit Barzilai]

At no point does ssd130x_write_data() change the bytes it receives via
the 'values' parameter. Constify the parameter so const-qualified
buffers pass through without casting away const.

Signed-off-by: Amit Barzilai <amit.barzilai22@gmail.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
---
 drivers/gpu/drm/solomon/ssd130x.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index 8cf1e9c84a81..73e7f2a8b730 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -252,7 +252,7 @@ static inline struct ssd130x_device *drm_to_ssd130x(struct drm_device *drm)
 /*
  * Helper to write data (SSD13XX_DATA) to the device.
  */
-static int ssd130x_write_data(struct ssd130x_device *ssd130x, u8 *values, int count)
+static int ssd130x_write_data(struct ssd130x_device *ssd130x, const u8 *values, int count)
 {
 	return regmap_bulk_write(ssd130x->regmap, SSD13XX_DATA, values, count);
 }
-- 
2.55.0

[PATCH v5 4/6] drm/ssd130x: Replace positional ssd130x_spi_id[] initialization with C99

[Amit Barzilai]

ssd130x_spi_id[] is initialized with positional initializers, which
easily create easy-to-miss bugs when changing the members of the target
struct (struct spi_device_id in this example).

Change this to C99 initializers to guarantee each member is initialized
with the correct value.

Signed-off-by: Amit Barzilai <amit.barzilai22@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
---
 drivers/gpu/drm/solomon/ssd130x-spi.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x-spi.c b/drivers/gpu/drm/solomon/ssd130x-spi.c
index b52f5fd592a1..be50e5aa2c87 100644
--- a/drivers/gpu/drm/solomon/ssd130x-spi.c
+++ b/drivers/gpu/drm/solomon/ssd130x-spi.c
@@ -160,17 +160,17 @@ MODULE_DEVICE_TABLE(of, ssd130x_of_match);
  */
 static const struct spi_device_id ssd130x_spi_id[] = {
 	/* ssd130x family */
-	{ "sh1106",  SH1106_ID },
-	{ "ssd1305", SSD1305_ID },
-	{ "ssd1306", SSD1306_ID },
-	{ "ssd1307", SSD1307_ID },
-	{ "ssd1309", SSD1309_ID },
+	{ .name = "sh1106", .driver_data = SH1106_ID },
+	{ .name = "ssd1305", .driver_data = SSD1305_ID },
+	{ .name = "ssd1306", .driver_data = SSD1306_ID },
+	{ .name = "ssd1307", .driver_data = SSD1307_ID },
+	{ .name = "ssd1309", .driver_data = SSD1309_ID },
 	/* ssd132x family */
-	{ "ssd1322", SSD1322_ID },
-	{ "ssd1325", SSD1325_ID },
-	{ "ssd1327", SSD1327_ID },
+	{ .name = "ssd1322", .driver_data = SSD1322_ID },
+	{ .name = "ssd1325", .driver_data = SSD1325_ID },
+	{ .name = "ssd1327", .driver_data = SSD1327_ID },
 	/* ssd133x family */
-	{ "ssd1331", SSD1331_ID },
+	{ .name = "ssd1331", .driver_data = SSD1331_ID },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(spi, ssd130x_spi_id);
-- 
2.55.0

[PATCH v5 5/6] drm/ssd130x: Implement ssd130x_write_cmd() on top of ssd130x_write_cmds()

[Amit Barzilai]

ssd130x_write_cmd() and ssd130x_write_cmds() each carried their own
regmap_write() loop over SSD13XX_COMMAND, differing only in how the caller
supplies the bytes.

Turn ssd130x_write_cmd() into a thin variadic wrapper that collects its
arguments into a small stack buffer and defers to ssd130x_write_cmds(), and
move the protocol comment onto the latter, which is where the loop now
lives.

No functional change: the bytes sent and the bus transactions used to send
them are identical for every chip on both the I2C and SPI transports.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Amit Barzilai <amit.barzilai22@gmail.com>
---
 drivers/gpu/drm/solomon/ssd130x.c | 65 +++++++++++++++----------------
 1 file changed, 31 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index 73e7f2a8b730..cdef0c09b050 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -258,41 +258,12 @@ static int ssd130x_write_data(struct ssd130x_device *ssd130x, const u8 *values,
 }
 
 /*
- * Helper to write command (SSD13XX_COMMAND). The fist variadic argument
- * is the command to write and the following are the command options.
+ * Helper to write a command (SSD13XX_COMMAND) from a buffer. The first byte
+ * is the command opcode and the following ones are its parameters.
  *
- * Note that the ssd13xx protocol requires each command and option to be
- * written as a SSD13XX_COMMAND device register value. That is why a call
- * to regmap_write(..., SSD13XX_COMMAND, ...) is done for each argument.
- */
-static int ssd130x_write_cmd(struct ssd130x_device *ssd130x, int count,
-			     /* u8 cmd, u8 option, ... */...)
-{
-	va_list ap;
-	u8 value;
-	int ret;
-
-	va_start(ap, count);
-
-	do {
-		value = va_arg(ap, int);
-		ret = regmap_write(ssd130x->regmap, SSD13XX_COMMAND, value);
-		if (ret)
-			goto out_end;
-	} while (--count);
-
-out_end:
-	va_end(ap);
-
-	return ret;
-}
-
-/*
- * Write a command byte sequence from a buffer.
- *
- * Like ssd130x_write_cmd() but takes a pre-built byte array instead of
- * variadic arguments, handy when the command is already in an array or
- * when the caller wants to use sizeof() for the length.
+ * Note that the ssd13xx protocol requires the opcode and each parameter to
+ * be written as a SSD13XX_COMMAND device register value. That is why a call
+ * to regmap_write(..., SSD13XX_COMMAND, ...) is done for each byte.
  */
 static int ssd130x_write_cmds(struct ssd130x_device *ssd130x, const u8 *cmd,
 			      size_t len)
@@ -309,6 +280,32 @@ static int ssd130x_write_cmds(struct ssd130x_device *ssd130x, const u8 *cmd,
 	return 0;
 }
 
+/*
+ * Variadic wrapper around ssd130x_write_cmds(). The first variadic argument
+ * is the command opcode and the following are its parameters.
+ *
+ * The arguments are gathered into a fixed size buffer, so at most 8 bytes
+ * can be sent per call, i.e. an opcode and seven parameters. That covers
+ * every command this driver sends through it. Commands taking more parameters,
+ * such as the grey scale tables, must use ssd130x_write_cmds() instead.
+ */
+static int ssd130x_write_cmd(struct ssd130x_device *ssd130x, int count,
+			     /* u8 cmd, u8 param, ... */...)
+{
+	u8 buf[8];
+	va_list ap;
+
+	if (drm_WARN_ON(&ssd130x->drm, count > sizeof(buf)))
+		return -EINVAL;
+
+	va_start(ap, count);
+	for (int i = 0; i < count; i++)
+		buf[i] = va_arg(ap, int);
+	va_end(ap);
+
+	return ssd130x_write_cmds(ssd130x, buf, count);
+}
+
 /*
  * Run a packed command sequence.  The format is a flat byte array where each
  * entry starts with a length byte followed by that many command bytes.  A
-- 
2.55.0

[PATCH v5 6/6] drm/ssd130x: Add SSD135X_FAMILY and SSD1351 support

[Amit Barzilai]

The Solomon SSD1351 is a 128x128 RGB color OLED controller. It shares the
SSD133X pixel layout: one 65k color (RGB565) pixel per Segment, written as
a bulk transfer once a column/row addressing window has been programmed.
Add it as a new SSD135X_FAMILY rather than as a separate driver, so that
the ssd130x plane, CRTC and encoder infrastructure is reused.

Give the family its own primary plane update and disable, encoder enable
and backlight callbacks instead of teaching the ssd133x ones about a second
family. Only the callbacks that carry no family specific logic are reused
as is: ssd133x_primary_plane_atomic_check(), ssd133x_crtc_atomic_check()
and ssd130x_encoder_atomic_disable().

The data path differs from the ssd133x family in one respect. The SSD1351
only starts accepting pixel data after an explicit Write RAM command
(0x5c), while the SSD133X enters data mode as soon as the address window
has been programmed. Emit it from ssd135x_update_rect(), which both the
damage update and the clear screen paths go through.

SSD1351 differs from previous controllers in the command protocol. While
the opcode is still sent on the command path, the parameters are sent on
the data path. Introduce the cmd_params_are_data flag to struct
ssd130x_deviceinfo and let ssd130x_write_cmds() split the buffer in
accordance to the device specifications.

The SSD1351 also needs its own init sequence (ssd135x_init). The remap
byte is fixed at horizontal address increment, COM split, reversed COM
scan direction, BGR sub-pixel order and 65k color depth; rotation is not
supported.

Contrast is calibrated per color channel as for the ssd133x family, but
the three channels are parameters of a single command (0xc1) instead of
one command per channel. Add ssd135x_set_contrast() for that and use it
from both the init and the backlight update paths.

The SSD1351 is SPI-only, so only the SPI transport match tables gain an
entry; no new config symbol is needed.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Amit Barzilai <amit.barzilai22@gmail.com>
---
 drivers/gpu/drm/solomon/ssd130x-spi.c |   7 +
 drivers/gpu/drm/solomon/ssd130x.c     | 311 +++++++++++++++++++++++++-
 drivers/gpu/drm/solomon/ssd130x.h     |  10 +-
 3 files changed, 321 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x-spi.c b/drivers/gpu/drm/solomon/ssd130x-spi.c
index be50e5aa2c87..c41064aa8221 100644
--- a/drivers/gpu/drm/solomon/ssd130x-spi.c
+++ b/drivers/gpu/drm/solomon/ssd130x-spi.c
@@ -146,6 +146,11 @@ static const struct of_device_id ssd130x_of_match[] = {
 		.compatible = "solomon,ssd1331",
 		.data = &ssd130x_variants[SSD1331_ID],
 	},
+	/* ssd135x family */
+	{
+		.compatible = "solomon,ssd1351",
+		.data = &ssd130x_variants[SSD1351_ID],
+	},
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, ssd130x_of_match);
@@ -171,6 +176,8 @@ static const struct spi_device_id ssd130x_spi_id[] = {
 	{ .name = "ssd1327", .driver_data = SSD1327_ID },
 	/* ssd133x family */
 	{ .name = "ssd1331", .driver_data = SSD1331_ID },
+	/* ssd135x family */
+	{ .name = "ssd1351", .driver_data = SSD1351_ID },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(spi, ssd130x_spi_id);
diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index cdef0c09b050..546f3df62cfa 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -151,6 +151,37 @@
 #define SSD133X_SET_REMAP_COLOR_DEPTH_MASK	GENMASK(7, 6)
 #define SSD133X_COLOR_DEPTH_65K			0x1
 
+/* ssd135x commands */
+#define SSD135X_SET_COL_RANGE			0x15
+#define SSD135X_WRITE_RAM			0x5c
+#define SSD135X_SET_ROW_RANGE			0x75
+#define SSD135X_SET_DISPLAY_START		0xa1
+#define SSD135X_SET_DISPLAY_OFFSET		0xa2
+#define SSD135X_SET_DISPLAY_NORMAL		0xa6
+#define SSD135X_SET_FUNCTION			0xab
+#define SSD135X_SET_PHASE_LENGTH		0xb1
+#define SSD135X_SET_CLOCK_FREQ			0xb3
+#define SSD135X_SET_VSL				0xb4
+#define SSD135X_SET_GPIO			0xb5
+#define SSD135X_SET_PRECHARGE2			0xb6
+#define SSD135X_SET_PRECHARGE_VOLTAGE		0xbb
+#define SSD135X_SET_VCOMH_VOLTAGE		0xbe
+#define SSD135X_SET_CONTRAST			0xc1
+#define SSD135X_SET_CONTRAST_MASTER		0xc7
+#define SSD135X_SET_MUX_RATIO			0xca
+#define SSD135X_SET_COMMAND_LOCK		0xfd
+
+/* ssd135x A/B/C channel contrast at full brightness (white balance) */
+#define SSD135X_DEFAULT_CONTRAST_A		0xc8
+#define SSD135X_DEFAULT_CONTRAST_B		0x80
+#define SSD135X_DEFAULT_CONTRAST_C		0xc8
+
+/* ssd135x remap byte (data of SSD13XX_SET_SEG_REMAP) */
+#define SSD135X_SET_REMAP_COLOR_BGR		BIT(2)
+#define SSD135X_SET_REMAP_COM_SCAN		BIT(4)
+#define SSD135X_SET_REMAP_COM_SPLIT		BIT(5)
+#define SSD135X_SET_REMAP_65K			BIT(6)
+
 #define MAX_CONTRAST 255
 
 const struct ssd130x_deviceinfo ssd130x_variants[] = {
@@ -218,7 +249,14 @@ const struct ssd130x_deviceinfo ssd130x_variants[] = {
 		.default_width = 96,
 		.default_height = 64,
 		.family_id = SSD133X_FAMILY,
-	}
+	},
+	/* ssd135x family */
+	[SSD1351_ID] = {
+		.default_width = 128,
+		.default_height = 128,
+		.family_id = SSD135X_FAMILY,
+		.cmd_params_are_data = true,
+	},
 };
 EXPORT_SYMBOL_NS_GPL(ssd130x_variants, "DRM_SSD130X");
 
@@ -261,9 +299,10 @@ static int ssd130x_write_data(struct ssd130x_device *ssd130x, const u8 *values,
  * Helper to write a command (SSD13XX_COMMAND) from a buffer. The first byte
  * is the command opcode and the following ones are its parameters.
  *
- * Note that the ssd13xx protocol requires the opcode and each parameter to
- * be written as a SSD13XX_COMMAND device register value. That is why a call
- * to regmap_write(..., SSD13XX_COMMAND, ...) is done for each byte.
+ * By default every byte is written as a SSD13XX_COMMAND register value, hence
+ * the regmap_write() per byte. Controllers that set cmd_params_are_data expect
+ * the parameters on the data path instead, so only the opcode is written as
+ * SSD13XX_COMMAND and the rest as SSD13XX_DATA.
  */
 static int ssd130x_write_cmds(struct ssd130x_device *ssd130x, const u8 *cmd,
 			      size_t len)
@@ -271,6 +310,17 @@ static int ssd130x_write_cmds(struct ssd130x_device *ssd130x, const u8 *cmd,
 	unsigned int i;
 	int ret;
 
+	if (ssd130x->device_info->cmd_params_are_data) {
+		if (!len)
+			return 0;
+
+		ret = regmap_write(ssd130x->regmap, SSD13XX_COMMAND, cmd[0]);
+		if (ret || len == 1)
+			return ret;
+
+		return ssd130x_write_data(ssd130x, cmd + 1, len - 1);
+	}
+
 	for (i = 0; i < len; i++) {
 		ret = regmap_write(ssd130x->regmap, SSD13XX_COMMAND, cmd[i]);
 		if (ret)
@@ -617,6 +667,20 @@ static int ssd133x_set_contrast(struct ssd130x_device *ssd130x, u32 brightness)
 	return ssd130x_run_cmd_seq(ssd130x, cmds);
 }
 
+/*
+ * Same white balance calibration as for the ssd133x family, except that the
+ * ssd135x controllers take the three channels as parameters of a single
+ * command instead of one command per channel.
+ */
+static int ssd135x_set_contrast(struct ssd130x_device *ssd130x, u32 brightness)
+{
+	u8 a = ssd130x_scale_contrast(SSD135X_DEFAULT_CONTRAST_A, brightness);
+	u8 b = ssd130x_scale_contrast(SSD135X_DEFAULT_CONTRAST_B, brightness);
+	u8 c = ssd130x_scale_contrast(SSD135X_DEFAULT_CONTRAST_C, brightness);
+
+	return ssd130x_write_cmd(ssd130x, 4, SSD135X_SET_CONTRAST, a, b, c);
+}
+
 static int ssd133x_init(struct ssd130x_device *ssd130x)
 {
 	int ret;
@@ -654,6 +718,47 @@ static int ssd133x_init(struct ssd130x_device *ssd130x)
 	return ssd130x_run_cmd_seq(ssd130x, cmds);
 }
 
+static int ssd135x_init(struct ssd130x_device *ssd130x)
+{
+	/*
+	 * Horizontal address increment, COM split, reversed COM scan direction,
+	 * BGR sub-pixel order and 65k (RGB565) color depth. Rotation is not
+	 * supported, so the remap byte is fixed.
+	 */
+	const u8 remap = SSD135X_SET_REMAP_65K | SSD135X_SET_REMAP_COM_SPLIT |
+			 SSD135X_SET_REMAP_COLOR_BGR | SSD135X_SET_REMAP_COM_SCAN;
+	const u8 cmds[] = {
+		/* Unlock the controller, then the extended command set */
+		2, SSD135X_SET_COMMAND_LOCK, 0x12,
+		2, SSD135X_SET_COMMAND_LOCK, 0xb1,
+		1, SSD13XX_DISPLAY_OFF,
+		2, SSD135X_SET_CLOCK_FREQ, 0xf1,
+		2, SSD135X_SET_MUX_RATIO, ssd130x->height - 1,
+		3, SSD135X_SET_COL_RANGE, 0x00, ssd130x->width - 1,
+		3, SSD135X_SET_ROW_RANGE, 0x00, ssd130x->height - 1,
+		2, SSD135X_SET_DISPLAY_START, 0x00,
+		2, SSD135X_SET_DISPLAY_OFFSET, 0x00,
+		2, SSD135X_SET_GPIO, 0x00,
+		2, SSD135X_SET_FUNCTION, 0x01,
+		2, SSD135X_SET_PHASE_LENGTH, 0x32,
+		4, SSD135X_SET_VSL, 0xa0, 0xb5, 0x55,
+		2, SSD135X_SET_PRECHARGE_VOLTAGE, 0x17,
+		2, SSD135X_SET_VCOMH_VOLTAGE, 0x05,
+		2, SSD135X_SET_CONTRAST_MASTER, 0x0f,
+		2, SSD135X_SET_PRECHARGE2, 0x01,
+		1, SSD135X_SET_DISPLAY_NORMAL,
+		2, SSD13XX_SET_SEG_REMAP, remap,
+		0,
+	};
+	int ret;
+
+	ret = ssd130x_run_cmd_seq(ssd130x, cmds);
+	if (ret < 0)
+		return ret;
+
+	return ssd135x_set_contrast(ssd130x, ssd130x->contrast);
+}
+
 static int ssd130x_update_rect(struct ssd130x_device *ssd130x,
 			       struct drm_rect *rect, u8 *buf,
 			       u8 *data_array)
@@ -863,6 +968,44 @@ static int ssd133x_update_rect(struct ssd130x_device *ssd130x,
 	return ret;
 }
 
+static int ssd135x_update_rect(struct ssd130x_device *ssd130x,
+			       struct drm_rect *rect, u8 *data_array,
+			       unsigned int pitch)
+{
+	unsigned int x = rect->x1;
+	unsigned int y = rect->y1;
+	unsigned int columns = drm_rect_width(rect);
+	unsigned int rows = drm_rect_height(rect);
+	int ret;
+
+	/*
+	 * The pixel layout is the same as for the ssd133x family: one 65k
+	 * color (RGB565) pixel per Segment, sent Segment by Segment when the
+	 * (default) horizontal address increment mode is used.
+	 *
+	 * But unlike the ssd133x family, which starts accepting pixel data as
+	 * soon as the address window has been programmed, the ssd135x family
+	 * needs an explicit Write RAM command before the data is written.
+	 */
+
+	/* Set column start and end */
+	ret = ssd130x_write_cmd(ssd130x, 3, SSD135X_SET_COL_RANGE, x, x + columns - 1);
+	if (ret < 0)
+		return ret;
+
+	/* Set row start and end */
+	ret = ssd130x_write_cmd(ssd130x, 3, SSD135X_SET_ROW_RANGE, y, y + rows - 1);
+	if (ret < 0)
+		return ret;
+
+	ret = ssd130x_write_cmd(ssd130x, 1, SSD135X_WRITE_RAM);
+	if (ret < 0)
+		return ret;
+
+	/* Write out update in one go since horizontal addressing mode is used */
+	return ssd130x_write_data(ssd130x, data_array, pitch * rows);
+}
+
 static void ssd130x_clear_screen(struct ssd130x_device *ssd130x, u8 *data_array)
 {
 	unsigned int pages = DIV_ROUND_UP(ssd130x->height, SSD130X_PAGE_HEIGHT);
@@ -932,6 +1075,23 @@ static void ssd133x_clear_screen(struct ssd130x_device *ssd130x, u8 *data_array)
 	ssd130x_write_data(ssd130x, data_array, pitch * ssd130x->height);
 }
 
+static void ssd135x_clear_screen(struct ssd130x_device *ssd130x, u8 *data_array)
+{
+	struct drm_rect screen = DRM_RECT_INIT(0, 0, ssd130x->width, ssd130x->height);
+	const struct drm_format_info *fi;
+	unsigned int pitch;
+
+	fi = drm_format_info(DRM_FORMAT_RGB565);
+	if (!fi)
+		return;
+
+	pitch = drm_format_info_min_pitch(fi, 0, ssd130x->width);
+
+	memset(data_array, 0, pitch * ssd130x->height);
+
+	ssd135x_update_rect(ssd130x, &screen, data_array, pitch);
+}
+
 static int ssd130x_fb_blit_rect(struct drm_framebuffer *fb,
 				const struct iosys_map *vmap,
 				struct drm_rect *rect,
@@ -1005,6 +1165,30 @@ static int ssd133x_fb_blit_rect(struct drm_framebuffer *fb,
 	return 0;
 }
 
+static int ssd135x_fb_blit_rect(struct drm_framebuffer *fb,
+				const struct iosys_map *vmap,
+				struct drm_rect *rect, u8 *data_array,
+				struct drm_format_conv_state *fmtcnv_state)
+{
+	struct ssd130x_device *ssd130x = drm_to_ssd130x(fb->dev);
+	const struct drm_format_info *fi;
+	unsigned int dst_pitch;
+	struct iosys_map dst;
+
+	fi = drm_format_info(DRM_FORMAT_RGB565);
+	if (!fi)
+		return -EINVAL;
+
+	dst_pitch = drm_format_info_min_pitch(fi, 0, drm_rect_width(rect));
+
+	iosys_map_set_vaddr(&dst, data_array);
+	drm_fb_xrgb8888_to_rgb565be(&dst, &dst_pitch, vmap, fb, rect, fmtcnv_state);
+
+	ssd135x_update_rect(ssd130x, rect, data_array, dst_pitch);
+
+	return 0;
+}
+
 static int ssd130x_primary_plane_atomic_check(struct drm_plane *plane,
 					      struct drm_atomic_commit *state)
 {
@@ -1247,6 +1431,45 @@ static void ssd133x_primary_plane_atomic_update(struct drm_plane *plane,
 	drm_dev_exit(idx);
 }
 
+static void ssd135x_primary_plane_atomic_update(struct drm_plane *plane,
+						struct drm_atomic_commit *state)
+{
+	struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
+	struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, plane);
+	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
+	struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, plane_state->crtc);
+	struct ssd130x_crtc_state *ssd130x_crtc_state =  to_ssd130x_crtc_state(crtc_state);
+	struct drm_framebuffer *fb = plane_state->fb;
+	struct drm_atomic_helper_damage_iter iter;
+	struct drm_device *drm = plane->dev;
+	struct drm_rect dst_clip;
+	struct drm_rect damage;
+	int idx;
+
+	if (!drm_dev_enter(drm, &idx))
+		return;
+
+	if (drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE))
+		goto out_drm_dev_exit;
+
+	drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
+	drm_atomic_for_each_plane_damage(&iter, &damage) {
+		dst_clip = plane_state->dst;
+
+		if (!drm_rect_intersect(&dst_clip, &damage))
+			continue;
+
+		ssd135x_fb_blit_rect(fb, &shadow_plane_state->data[0], &dst_clip,
+				     ssd130x_crtc_state->data_array,
+				     &shadow_plane_state->fmtcnv_state);
+	}
+
+	drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
+
+out_drm_dev_exit:
+	drm_dev_exit(idx);
+}
+
 static void ssd130x_primary_plane_atomic_disable(struct drm_plane *plane,
 						 struct drm_atomic_commit *state)
 {
@@ -1319,6 +1542,31 @@ static void ssd133x_primary_plane_atomic_disable(struct drm_plane *plane,
 	drm_dev_exit(idx);
 }
 
+static void ssd135x_primary_plane_atomic_disable(struct drm_plane *plane,
+						 struct drm_atomic_commit *state)
+{
+	struct drm_device *drm = plane->dev;
+	struct ssd130x_device *ssd130x = drm_to_ssd130x(drm);
+	struct drm_plane_state *plane_state;
+	struct drm_crtc_state *crtc_state;
+	struct ssd130x_crtc_state *ssd130x_crtc_state;
+	int idx;
+
+	plane_state = drm_atomic_get_new_plane_state(state, plane);
+	if (!plane_state->crtc)
+		return;
+
+	crtc_state = drm_atomic_get_new_crtc_state(state, plane_state->crtc);
+	ssd130x_crtc_state = to_ssd130x_crtc_state(crtc_state);
+
+	if (!drm_dev_enter(drm, &idx))
+		return;
+
+	ssd135x_clear_screen(ssd130x, ssd130x_crtc_state->data_array);
+
+	drm_dev_exit(idx);
+}
+
 /* Called during init to allocate the plane's atomic state. */
 static void ssd130x_primary_plane_reset(struct drm_plane *plane)
 {
@@ -1387,7 +1635,13 @@ static const struct drm_plane_helper_funcs ssd130x_primary_plane_helper_funcs[]
 		.atomic_check = ssd133x_primary_plane_atomic_check,
 		.atomic_update = ssd133x_primary_plane_atomic_update,
 		.atomic_disable = ssd133x_primary_plane_atomic_disable,
-	}
+	},
+	[SSD135X_FAMILY] = {
+		DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
+		.atomic_check = ssd133x_primary_plane_atomic_check,
+		.atomic_update = ssd135x_primary_plane_atomic_update,
+		.atomic_disable = ssd135x_primary_plane_atomic_disable,
+	},
 };
 
 static const struct drm_plane_funcs ssd130x_primary_plane_funcs = {
@@ -1542,6 +1796,10 @@ static const struct drm_crtc_helper_funcs ssd130x_crtc_helper_funcs[] = {
 		.mode_valid = ssd130x_crtc_mode_valid,
 		.atomic_check = ssd133x_crtc_atomic_check,
 	},
+	[SSD135X_FAMILY] = {
+		.mode_valid = ssd130x_crtc_mode_valid,
+		.atomic_check = ssd133x_crtc_atomic_check,
+	},
 };
 
 static const struct drm_crtc_funcs ssd130x_crtc_funcs = {
@@ -1629,6 +1887,31 @@ static void ssd133x_encoder_atomic_enable(struct drm_encoder *encoder,
 	ssd130x_power_off(ssd130x);
 }
 
+static void ssd135x_encoder_atomic_enable(struct drm_encoder *encoder,
+					  struct drm_atomic_commit *state)
+{
+	struct drm_device *drm = encoder->dev;
+	struct ssd130x_device *ssd130x = drm_to_ssd130x(drm);
+	int ret;
+
+	ret = ssd130x_power_on(ssd130x);
+	if (ret)
+		return;
+
+	ret = ssd135x_init(ssd130x);
+	if (ret)
+		goto power_off;
+
+	ssd130x_write_cmd(ssd130x, 1, SSD13XX_DISPLAY_ON);
+
+	backlight_enable(ssd130x->bl_dev);
+
+	return;
+
+power_off:
+	ssd130x_power_off(ssd130x);
+}
+
 static void ssd130x_encoder_atomic_disable(struct drm_encoder *encoder,
 					   struct drm_atomic_commit *state)
 {
@@ -1654,7 +1937,11 @@ static const struct drm_encoder_helper_funcs ssd130x_encoder_helper_funcs[] = {
 	[SSD133X_FAMILY] = {
 		.atomic_enable = ssd133x_encoder_atomic_enable,
 		.atomic_disable = ssd130x_encoder_atomic_disable,
-	}
+	},
+	[SSD135X_FAMILY] = {
+		.atomic_enable = ssd135x_encoder_atomic_enable,
+		.atomic_disable = ssd130x_encoder_atomic_disable,
+	},
 };
 
 static const struct drm_encoder_funcs ssd130x_encoder_funcs = {
@@ -1731,6 +2018,15 @@ static int ssd133x_update_bl(struct backlight_device *bdev)
 	return ssd133x_set_contrast(ssd130x, ssd130x->contrast);
 }
 
+static int ssd135x_update_bl(struct backlight_device *bdev)
+{
+	struct ssd130x_device *ssd130x = bl_get_data(bdev);
+
+	ssd130x->contrast = backlight_get_brightness(bdev);
+
+	return ssd135x_set_contrast(ssd130x, ssd130x->contrast);
+}
+
 static const struct backlight_ops ssd130xfb_bl_ops[] = {
 	[SSD130X_FAMILY] = {
 		.update_status	= ssd130x_update_bl,
@@ -1741,6 +2037,9 @@ static const struct backlight_ops ssd130xfb_bl_ops[] = {
 	[SSD133X_FAMILY] = {
 		.update_status	= ssd133x_update_bl,
 	},
+	[SSD135X_FAMILY] = {
+		.update_status	= ssd135x_update_bl,
+	},
 };
 
 static void ssd130x_parse_properties(struct ssd130x_device *ssd130x)
diff --git a/drivers/gpu/drm/solomon/ssd130x.h b/drivers/gpu/drm/solomon/ssd130x.h
index a4554018bb2a..fd81262f2ceb 100644
--- a/drivers/gpu/drm/solomon/ssd130x.h
+++ b/drivers/gpu/drm/solomon/ssd130x.h
@@ -26,7 +26,8 @@
 enum ssd130x_family_ids {
 	SSD130X_FAMILY,
 	SSD132X_FAMILY,
-	SSD133X_FAMILY
+	SSD133X_FAMILY,
+	SSD135X_FAMILY,
 };
 
 enum ssd130x_variants {
@@ -42,6 +43,8 @@ enum ssd130x_variants {
 	SSD1327_ID,
 	/* ssd133x family */
 	SSD1331_ID,
+	/* ssd135x family */
+	SSD1351_ID,
 	NR_SSD130X_VARIANTS
 };
 
@@ -54,6 +57,11 @@ struct ssd130x_deviceinfo {
 	bool need_pwm;
 	bool need_chargepump;
 	bool page_mode_only;
+	/*
+	 * Whether the controller takes a command's parameters on the data path
+	 * instead of as further command bytes.
+	 */
+	bool cmd_params_are_data;
 
 	enum ssd130x_family_ids family_id;
 };
-- 
2.55.0

Re: [PATCH v5 1/6] dt-bindings: display: Add Solomon SSD1351 OLED controller

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The binding is missing controller-specific default values for `solomon,width` and `solomon,height`.
--

--- Patch [1]: [PATCH v5 1/6] dt-bindings: display: Add Solomon SSD1351 OLED controller ---
commit c53d1459d9817dd8adf46b673b2d950a10a1775b
Author: Amit Barzilai <amit.barzilai22@gmail.com>

dt-bindings: display: Add Solomon SSD1351 OLED controller

This commit adds a device tree binding for the Solomon SSD1351 128x128
65k-color RGB OLED display controller. It leverages the shared
solomon,ssd-common.yaml properties used by other Solomon display controllers.

> diff --git a/Documentation/devicetree/bindings/display/solomon,ssd1351.yaml b/Documentation/devicetree/bindings/display/solomon,ssd1351.yaml
> new file mode 100644
> index 0000000000000..80850c2ab5b3e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/solomon,ssd1351.yaml
[ ... ]
> +allOf:
> +  - $ref: solomon,ssd-common.yaml#
> +
> +properties:
> +  compatible:
> +    enum:
> +      - solomon,ssd1351

[Severity: Low]
Should this properties block also declare default values for solomon,width
and solomon,height?

Other bindings that include solomon,ssd-common.yaml, such as
solomon,ssd133x.yaml, establish default geometry values for their specific
compatible strings in this block. Without these default values, device trees
that omit the width and height properties will lack a schema-defined default
geometry.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260823111959.17029-1-amit.barzilai22@gmail.com?part=1

Re: [PATCH v5 6/6] drm/ssd130x: Add SSD135X_FAMILY and SSD1351 support

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 4 potential issue(s) to consider:

New issues:
- [High] DMA on stack memory via regmap_bulk_write in ssd130x_write_cmds.

Pre-existing issues:
- [High] drm_gem_fb_begin_cpu_access sleeps in atomic context.
- [High] regulator_enable sleeps in atomic context.
- [High] Backlight and DRM atomic commit unprotected SPI updates interleave.
--

--- Patch [6]: [PATCH v5 6/6] drm/ssd130x: Add SSD135X_FAMILY and SSD1351 support ---
commit c25fd0a18b10199afa7a08a23e60b6d45a463381
Author: Amit Barzilai <amit.barzilai22@gmail.com>

drm/ssd130x: Add SSD135X_FAMILY and SSD1351 support

This commit adds support for the SSD1351 controller by introducing a new
SSD135X_FAMILY to the ssd130x driver. It adds a new init sequence, custom
command protocols that pass parameters on the data path, and family-specific
plane and encoder callbacks.

> diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
> --- a/drivers/gpu/drm/solomon/ssd130x.c
> +++ b/drivers/gpu/drm/solomon/ssd130x.c
[ ... ]
> @@ -271,6 +310,17 @@ static int ssd130x_write_cmds(struct ssd130x_device *ssd130x, const u8 *cmd,
>  	unsigned int i;
>  	int ret;
>  
> +	if (ssd130x->device_info->cmd_params_are_data) {
> +		if (!len)
> +			return 0;
> +
> +		ret = regmap_write(ssd130x->regmap, SSD13XX_COMMAND, cmd[0]);
> +		if (ret || len == 1)
> +			return ret;
> +
> +		return ssd130x_write_data(ssd130x, cmd + 1, len - 1);
> +	}

[Severity: High]
Will this cause a DMA fault on stack memory? Callers like ssd130x_write_cmd()
allocate the command array on the kernel stack (e.g. u8 buf[8]). Passing
cmd + 1 to ssd130x_write_data() results in a regmap_bulk_write(). On SPI
devices, this passes the buffer directly to the SPI DMA engine. Because
vmalloc-backed kernel stacks forbid DMA, this might cause an immediate
kernel panic or fault during device probe and runtime updates.

[Severity: High]
This is a pre-existing issue, but does this split transaction allow
concurrent updates to interleave on the SPI bus? If a user-space write to
the sysfs backlight interface triggers ssd135x_update_bl() concurrently with
a display update from ssd135x_update_rect(), another thread's regmap_write()
could execute in between this regmap_write() and ssd130x_write_data(). This
could cause the controller to misinterpret parameters as opcodes or vice
versa.

[ ... ]
> @@ -1247,6 +1431,45 @@ static void ssd133x_primary_plane_atomic_update(struct drm_plane *plane,
>  	drm_dev_exit(idx);
>  }
>  
> +static void ssd135x_primary_plane_atomic_update(struct drm_plane *plane,
> +						struct drm_atomic_commit *state)
> +{
[ ... ]
> +	if (!drm_dev_enter(drm, &idx))
> +		return;
> +
> +	if (drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE))
> +		goto out_drm_dev_exit;

[Severity: High]
This isn't a bug introduced by this patch, but does this call to
drm_gem_fb_begin_cpu_access() sleep in an atomic context? Plane atomic
update callbacks run in atomic context during non-blocking commit tails.
Since drm_gem_fb_begin_cpu_access() can sleep while waiting on dma-buf
fences or acquiring locks, this might cause kernel warnings or deadlocks
during screen updates.

[ ... ]
> @@ -1629,6 +1887,31 @@ static void ssd133x_encoder_atomic_enable(struct drm_encoder *encoder,
>  	ssd130x_power_off(ssd130x);
>  }
>  
> +static void ssd135x_encoder_atomic_enable(struct drm_encoder *encoder,
> +					  struct drm_atomic_commit *state)
> +{
> +	struct drm_device *drm = encoder->dev;
> +	struct ssd130x_device *ssd130x = drm_to_ssd130x(drm);
> +	int ret;
> +
> +	ret = ssd130x_power_on(ssd130x);

[Severity: High]
This is a pre-existing issue, but can this power management sequence sleep
in an atomic context? Encoder atomic enable callbacks must not sleep, yet
ssd130x_power_on() calls regulator_enable() which uses mutexes internally.
Could this lead to deadlocks or crashes when the display is enabled?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260823111959.17029-1-amit.barzilai22@gmail.com?part=6

Re: [PATCH v5 2/6] drm/ssd130x: Change SSD133X color format to RGB565 from RGB332

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:

Pre-existing issues:
- [High] Missing drm_format_conv_state_reserve() pre-allocation forces unsafe GFP_KERNEL allocation in atomic context.
- [High] Sleeping functions called from plane atomic update callback.
--

--- Patch [2]: [PATCH v5 2/6] drm/ssd130x: Change SSD133X color format to RGB565 from RGB332 ---
commit e1ae8460e953e75a280fd3111fa7957d70e68fcc
Author: Amit Barzilai <amit.barzilai22@gmail.com>

drm/ssd130x: Change SSD133X color format to RGB565 from RGB332
    
SSD133X screens were driven at 8bpp RGB332 despite supporting 16bpp RGB565.
Switch the SSD133X data path to RGB565.

> diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
> index 0b0fc6fe3df23..8cf1e9c84a810 100644
> --- a/drivers/gpu/drm/solomon/ssd130x.c
> +++ b/drivers/gpu/drm/solomon/ssd130x.c

[ ... ]

> @@ -978,17 +990,18 @@ static int ssd133x_fb_blit_rect(struct drm_framebuffer *fb,
>  				struct drm_format_conv_state *fmtcnv_state)
>  {
>  	struct ssd130x_device *ssd130x = drm_to_ssd130x(fb->dev);
> -	const struct drm_format_info *fi = drm_format_info(DRM_FORMAT_RGB332);
> +	const struct drm_format_info *fi;
>  	unsigned int dst_pitch;
>  	struct iosys_map dst;
>  
> +	fi = drm_format_info(DRM_FORMAT_RGB565);
>  	if (!fi)
>  		return -EINVAL;
>  
>  	dst_pitch = drm_format_info_min_pitch(fi, 0, drm_rect_width(rect));
>  
>  	iosys_map_set_vaddr(&dst, data_array);
> -	drm_fb_xrgb8888_to_rgb332(&dst, &dst_pitch, vmap, fb, rect, fmtcnv_state);
> +	drm_fb_xrgb8888_to_rgb565be(&dst, &dst_pitch, vmap, fb, rect, fmtcnv_state);

[Severity: High]
This is a pre-existing issue, but does this conversion allocate memory with
GFP_KERNEL in an atomic context?

Because ssd133x_primary_plane_atomic_check() does not pre-allocate the format
conversion state using drm_format_conv_state_reserve(), this call to
drm_fb_xrgb8888_to_rgb565be() can fall back to a dynamic GFP_KERNEL allocation
within __drm_fb_xfrm(). This leads to might_sleep() warnings since it executes
during the plane's atomic_update callback.

>  
>  	ssd133x_update_rect(ssd130x, rect, data_array, dst_pitch);

[Severity: High]
This isn't a bug introduced by this patch, but does this function sequence
perform sleeping operations from an atomic context?

The ssd133x_primary_plane_atomic_update() callback runs in an atomic context
where sleeping is forbidden. However, it calls drm_gem_fb_begin_cpu_access()
(which waits on dma_resv and can sleep) and then calls into this function,
which reaches ssd133x_update_rect(). The update function performs hardware
writes using regmap_bulk_write() on sleepable I2C/SPI buses.

>  
>  	return 0;
>  }

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260823111959.17029-1-amit.barzilai22@gmail.com?part=2

Re: [PATCH v5 2/6] drm/ssd130x: Change SSD133X color format to RGB565 from RGB332

[Andy Shevchenko]

On Sun, Aug 23, 2026 at 02:19:55PM +0300, Amit Barzilai wrote:
> SSD133X screens were driven at 8bpp RGB332 despite supporting 16bpp RGB565.
> Switch the SSD133X data path to RGB565.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>

-- 
With Best Regards,
Andy Shevchenko