[PATCH v6 12/15] drm/client: splash: take the background colour from the image source

["Màxim Pedraza Padilla" <maximpedraza@gmail.com>]

A logo designed for a light background looks wrong framed in black, and
products that share a board support package differ in their colours as
much as in their logos. The background colour belongs with the image,
so a device tree image takes it from the optional "background-color" of
its node. A value that is not one cell of RGB888 is reported and left
out.

CONFIG_DRM_CLIENT_SPLASH_BACKGROUND_COLOR remains the colour wherever
the source says nothing, as with the BGRT, which carries no colour, and
the BMP loaded as firmware.

Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Màxim Pedraza Padilla <maximpedraza@gmail.com>
---
 drivers/gpu/drm/clients/Kconfig      |  3 ++-
 drivers/gpu/drm/clients/drm_splash.c | 33 +++++++++++++++++++++-------
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/clients/Kconfig b/drivers/gpu/drm/clients/Kconfig
index 172781bbc2d7..bb5fe5019756 100644
--- a/drivers/gpu/drm/clients/Kconfig
+++ b/drivers/gpu/drm/clients/Kconfig
@@ -104,7 +104,8 @@ config DRM_CLIENT_SPLASH_BACKGROUND_COLOR
 	default 0x000000
 	range 0x000000 0xffffff
 	help
-	  The splash background color, in RGB888 format.
+	  The splash background color, in RGB888 format, unless the image
+	  source has its own: a device tree image can carry its color.
 
 config DRM_CLIENT_SPLASH_SRC_DT
 	bool "Device tree as splash source"
diff --git a/drivers/gpu/drm/clients/drm_splash.c b/drivers/gpu/drm/clients/drm_splash.c
index a50036155763..3f54bec87413 100644
--- a/drivers/gpu/drm/clients/drm_splash.c
+++ b/drivers/gpu/drm/clients/drm_splash.c
@@ -117,6 +117,8 @@ struct drm_splash {
 	s32 off_x, off_y;
 	/* One of DRM_MODE_ROTATE_*: turns the image, not the screen */
 	unsigned int rotation;
+	/* RGB888, from the image source or the kernel's default */
+	u32 bg_color;
 };
 
 static struct drm_splash *client_to_drm_splash(struct drm_client_dev *client)
@@ -272,12 +274,23 @@ static void drm_splash_dt_pair(struct drm_splash *splash,
 	*y = val[1];
 }
 
-/* The optional placement properties of the node, read once */
-static void drm_splash_dt_placement(struct drm_splash *splash,
-				    struct device_node *np)
+/* The optional properties of the node, read once */
+static void drm_splash_dt_props(struct drm_splash *splash,
+				struct device_node *np)
 {
 	u32 val;
 
+	/* The colour travels with the image; a bad one is reported */
+	if (of_property_present(np, "background-color")) {
+		if (of_property_count_u32_elems(np, "background-color") != 1 ||
+		    of_property_read_u32(np, "background-color", &val) ||
+		    val > 0xffffff)
+			drm_warn(splash->client.dev, "splash: %pOF: invalid %s\n",
+				 np, "background-color");
+		else
+			splash->bg_color = val;
+	}
+
 	drm_splash_dt_pair(splash, np, "logo-position", -1, 65535,
 			   &splash->pos_x, &splash->pos_y);
 	drm_splash_dt_pair(splash, np, "logo-offset", -65535, 65535,
@@ -375,8 +388,8 @@ static bool drm_splash_dt_open(struct drm_splash *splash)
 	return false;
 }
 
-static void drm_splash_dt_placement(struct drm_splash *splash,
-				    struct device_node *np)
+static void drm_splash_dt_props(struct drm_splash *splash,
+				struct device_node *np)
 {
 }
 
@@ -802,13 +815,17 @@ static int drm_splash_image_load(struct drm_splash *splash, const u8 **img_data,
  */
 static enum drm_splash_source drm_splash_pick_source(struct drm_splash *splash)
 {
+	/* Unless the source says otherwise, the kernel's default colour */
+	splash->bg_color = CONFIG_DRM_CLIENT_SPLASH_BACKGROUND_COLOR;
+
 	if (drm_splash_dt_open(splash)) {
-		drm_splash_dt_placement(splash, splash->dt_np);
+		drm_splash_dt_props(splash, splash->dt_np);
 		return DRM_SPLASH_SRC_DT;
 	}
 
 	if (drm_splash_bgrt_available(splash))
 		return DRM_SPLASH_SRC_BGRT;
+
 	if (IS_ENABLED(CONFIG_DRM_CLIENT_SPLASH_SRC_BMP))
 		return DRM_SPLASH_SRC_BMP;
 
@@ -875,8 +892,8 @@ static void drm_splash_work(struct work_struct *work)
 			continue;
 
 		if (!scanout->bg_drawn) {
-			u32 rgb = CONFIG_DRM_CLIENT_SPLASH_BACKGROUND_COLOR;
-			u32 color = drm_draw_color_from_xrgb8888(rgb, scanout->format);
+			u32 color = drm_draw_color_from_xrgb8888(splash->bg_color,
+								 scanout->format);
 
 			/* Only success marks it done: a later pass retries */
 			ret = drm_splash_fill_solid_color(scanout->buffer, color);
-- 
2.39.5