Thread (15 messages) 15 messages, 6 authors, 1d ago
WARM1d

[PATCH v2 2/4] drm/ssd130x: Add RGB565 support to SSD133X family

From: Amit Barzilai <hidden>
Date: 2026-06-22 15:25:27
Also in: dri-devel, linux-devicetree, linux-staging, lkml
Subsystem: drm driver for solomon ssd130x oled displays, drm drivers, drm drivers and misc gpu patches, the rest · Maintainers: Javier Martinez Canillas, David Airlie, Simona Vetter, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, Linus Torvalds

SSD133X screens were getting 8bpp (RGB332) instead of the 16bpp
(RGB565) that they support. This change adds a boolean to the
deviceinfo struct selecting whether the variant is driven at
DRM_FORMAT_RGB565.

Changed SSD133X to now utilize 65k color (RGB565).

Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Amit Barzilai <redacted>
---
 drivers/gpu/drm/solomon/ssd130x.c | 55 +++++++++++++++++++++++++------
 drivers/gpu/drm/solomon/ssd130x.h |  7 ++++
 2 files changed, 52 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index 04da4f2f7d08..2b0a8218f529 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -140,6 +140,12 @@
 #define SSD133X_SET_PRECHARGE_VOLTAGE		0xbb
 #define SSD133X_SET_VCOMH_VOLTAGE		0xbe
 
+/* 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_256			0x0
+#define SSD133X_COLOR_DEPTH_65K			0x1
+
 #define MAX_CONTRAST 255
 
 const struct ssd130x_deviceinfo ssd130x_variants[] = {
@@ -206,6 +212,7 @@ const struct ssd130x_deviceinfo ssd130x_variants[] = {
 	[SSD1331_ID] = {
 		.default_width = 96,
 		.default_height = 64,
+		.format_rgb565 = 1,
 		.family_id = SSD133X_FAMILY,
 	}
 };
@@ -584,6 +591,10 @@ static int ssd132x_init(struct ssd130x_device *ssd130x)
 
 static int ssd133x_init(struct ssd130x_device *ssd130x)
 {
+	u8 remap = SSD133X_SET_REMAP_COM_SPLIT |
+		   FIELD_PREP(SSD133X_SET_REMAP_COLOR_DEPTH_MASK,
+			      ssd130x->device_info->format_rgb565 ?
+			      SSD133X_COLOR_DEPTH_65K : SSD133X_COLOR_DEPTH_256);
 	const u8 cmds[] = {
 		2, SSD133X_CONTRAST_A, 0x91,
 		2, SSD133X_CONTRAST_B, 0x50,
@@ -595,9 +606,9 @@ static int ssd133x_init(struct ssd130x_device *ssd130x)
 		 * Horizontal Address Increment
 		 * Normal order SA,SB,SC (e.g. RGB)
 		 * COM Split Odd Even
-		 * 256 color format
+		 * 256 or 65k color format, depending on the variant
 		 */
-		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,
@@ -794,14 +805,20 @@ 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.
+	 *
+	 * When using the 65k color depth format, each pixel contains 3
+	 * sub-pixels for color A, B and C. These have 5 bit, 6 bit and
+	 * 5 bits respectively.
 	 */
 
 	/* Set column start and end */
@@ -872,9 +889,24 @@ static void ssd132x_clear_screen(struct ssd130x_device *ssd130x, u8 *data_array)
 	ssd130x_write_data(ssd130x, data_array, columns * height);
 }
 
+/*
+ * The SSD133X family can drive the panel in either RGB332 (1 byte per pixel)
+ * or RGB565 (2 bytes per pixel). The format is a per-variant policy choice
+ * selected through ssd130x_deviceinfo::format_rgb565, not a capability probe.
+ * Centralize the choice here so that the buffer sizing (allocation, clear and
+ * blit pitch) can never disagree.
+ */
+static const struct drm_format_info *ssd133x_format_info(struct ssd130x_device *ssd130x)
+{
+	if (ssd130x->device_info->format_rgb565)
+		return drm_format_info(DRM_FORMAT_RGB565);
+
+	return drm_format_info(DRM_FORMAT_RGB332);
+}
+
 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 = ssd133x_format_info(ssd130x);
 	unsigned int pitch;
 
 	if (!fi)
@@ -945,7 +977,7 @@ 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 = ssd133x_format_info(ssd130x);
 	unsigned int dst_pitch;
 	struct iosys_map dst;
 	int ret = 0;
@@ -956,7 +988,10 @@ static int ssd133x_fb_blit_rect(struct drm_framebuffer *fb,
 	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);
+	if (ssd130x->device_info->format_rgb565)
+		drm_fb_xrgb8888_to_rgb565be(&dst, &dst_pitch, vmap, fb, rect, fmtcnv_state);
+	else
+		drm_fb_xrgb8888_to_rgb332(&dst, &dst_pitch, vmap, fb, rect, fmtcnv_state);
 
 	ssd133x_update_rect(ssd130x, rect, data_array, dst_pitch);
 
@@ -1414,7 +1449,7 @@ 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 = ssd133x_format_info(ssd130x);
 	unsigned int pitch;
 	int ret;
 
diff --git a/drivers/gpu/drm/solomon/ssd130x.h b/drivers/gpu/drm/solomon/ssd130x.h
index a4554018bb2a..b0b487c06e04 100644
--- a/drivers/gpu/drm/solomon/ssd130x.h
+++ b/drivers/gpu/drm/solomon/ssd130x.h
@@ -54,6 +54,13 @@ struct ssd130x_deviceinfo {
 	bool need_pwm;
 	bool need_chargepump;
 	bool page_mode_only;
+	/*
+	 * Per-variant output format selector for the SSD133X data path. The
+	 * hardware can drive the panel in RGB332 (1 byte/pixel) or RGB565
+	 * (2 bytes/pixel); this is a policy choice per variant, not a
+	 * capability probe. When set, the variant is driven at RGB565.
+	 */
+	bool format_rgb565;
 
 	enum ssd130x_family_ids family_id;
 };
-- 
2.54.0
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