Re: [PATCH v4] drm/fb-helper: Replace bpp/depth parameter by color mode

Maíra Canal <mcanal@xxxxxxxxxx> · Fri, 6 Jan 2023 08:39:22 -0300

On 1/6/23 08:23, Thomas Zimmermann wrote:
Replace the combination of bpp and depth with a single color-mode
argument. Handle special cases in simpledrm and ofdrm. Hard-code
XRGB8888 as fallback format for cases where no given format works.

The color-mode argument accepts the same values as the kernel's video
parameter. These are mostly bpp values between 1 and 32. The exceptions
are 15, which has a color depth of 15 and a bpp value of 16; and 32,
which has a color depth of 24 and a bpp value of 32.

v4:
	* add back lost test for bpp_specified (Maira)
	* add Fixes tag (Daniel)
v3:
	* fix ofdrm build (Maxime)
v2:
	* minimize changes (Daniel)
	* use drm_driver_legacy_fb_format() (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>

Tested-by: Maíra Canal <mcanal@xxxxxxxxxx> # vc4 and vkms

Thanks for taking care of this!

Best Regards,
- Maíra Canal

Fixes: 37c90d589dc0 ("drm/fb-helper: Fix single-probe color-format selection")
Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Maxime Ripard <mripard@xxxxxxxxxx>
---
  drivers/gpu/drm/drm_fb_helper.c  | 42 ++++++++++++++++++--------------
  drivers/gpu/drm/tiny/ofdrm.c     |  7 +++++-
  drivers/gpu/drm/tiny/simpledrm.c |  7 +++++-
  3 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 1369ca4ae39b..427631706128 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1756,24 +1756,21 @@ static uint32_t drm_fb_helper_find_format(struct drm_fb_helper *fb_helper, const
  	return DRM_FORMAT_INVALID;
  }
  
-static uint32_t drm_fb_helper_find_cmdline_format(struct drm_fb_helper *fb_helper,
-						  const uint32_t *formats, size_t format_count,
-						  const struct drm_cmdline_mode *cmdline_mode)
+static uint32_t drm_fb_helper_find_color_mode_format(struct drm_fb_helper *fb_helper,
+						     const uint32_t *formats, size_t format_count,
+						     unsigned int color_mode)
  {
  	struct drm_device *dev = fb_helper->dev;
  	uint32_t bpp, depth;
  
-	if (!cmdline_mode->bpp_specified)
-		return DRM_FORMAT_INVALID;
-
-	switch (cmdline_mode->bpp) {
+	switch (color_mode) {
  	case 1:
  	case 2:
  	case 4:
  	case 8:
  	case 16:
  	case 24:
-		bpp = depth = cmdline_mode->bpp;
+		bpp = depth = color_mode;
  		break;
  	case 15:
  		bpp = 16;
@@ -1784,7 +1781,7 @@ static uint32_t drm_fb_helper_find_cmdline_format(struct drm_fb_helper *fb_helpe
  		depth = 24;
  		break;
  	default:
-		drm_info(dev, "unsupported bpp value of %d\n", cmdline_mode->bpp);
+		drm_info(dev, "unsupported color mode of %d\n", color_mode);
  		return DRM_FORMAT_INVALID;
  	}
  
@@ -1817,10 +1814,13 @@ static int __drm_fb_helper_find_sizes(struct drm_fb_helper *fb_helper, int prefe
  		drm_client_for_each_connector_iter(connector, &conn_iter) {
  			struct drm_cmdline_mode *cmdline_mode = &connector->cmdline_mode;
  
-			surface_format = drm_fb_helper_find_cmdline_format(fb_helper,
-									   plane->format_types,
-									   plane->format_count,
-									   cmdline_mode);
+			if (!cmdline_mode->bpp_specified)
+				continue;
+
+			surface_format = drm_fb_helper_find_color_mode_format(fb_helper,
+									      plane->format_types,
+									      plane->format_count,
+									      cmdline_mode->bpp);
  			if (surface_format != DRM_FORMAT_INVALID)
  				break; /* found supported format */
  		}
@@ -1829,17 +1829,23 @@ static int __drm_fb_helper_find_sizes(struct drm_fb_helper *fb_helper, int prefe
  		if (surface_format != DRM_FORMAT_INVALID)
  			break; /* found supported format */
  
-		/* try preferred bpp/depth */
-		surface_format = drm_fb_helper_find_format(fb_helper, plane->format_types,
-							   plane->format_count, preferred_bpp,
-							   dev->mode_config.preferred_depth);
+		/* try preferred color mode */
+		surface_format = drm_fb_helper_find_color_mode_format(fb_helper,
+								      plane->format_types,
+								      plane->format_count,
+								      preferred_bpp);
  		if (surface_format != DRM_FORMAT_INVALID)
  			break; /* found supported format */
  	}
  
  	if (surface_format == DRM_FORMAT_INVALID) {
+		/*
+		 * If none of the given color modes works, fall back
+		 * to XRGB8888. Drivers are expected to provide this
+		 * format for compatibility with legacy applications.
+		 */
  		drm_warn(dev, "No compatible format found\n");
-		return -EAGAIN;
+		surface_format = drm_driver_legacy_fb_format(dev, 32, 24);
  	}
  
  	info = drm_format_info(surface_format);
diff --git a/drivers/gpu/drm/tiny/ofdrm.c b/drivers/gpu/drm/tiny/ofdrm.c
index 39c5fd463fec..6e349ca42485 100644
--- a/drivers/gpu/drm/tiny/ofdrm.c
+++ b/drivers/gpu/drm/tiny/ofdrm.c
@@ -1352,6 +1352,7 @@ static int ofdrm_probe(struct platform_device *pdev)
  {
  	struct ofdrm_device *odev;
  	struct drm_device *dev;
+	unsigned int color_mode;
  	int ret;
  
  	odev = ofdrm_device_create(&ofdrm_driver, pdev);
@@ -1363,7 +1364,11 @@ static int ofdrm_probe(struct platform_device *pdev)
  	if (ret)
  		return ret;
  
-	drm_fbdev_generic_setup(dev, drm_format_info_bpp(odev->format, 0));
+	color_mode = drm_format_info_bpp(odev->format, 0);
+	if (color_mode == 16)
+		color_mode = odev->format->depth; // can be 15 or 16
+
+	drm_fbdev_generic_setup(dev, color_mode);
  
  	return 0;
  }
diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index 7355617f38d3..f658b99c796a 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -802,6 +802,7 @@ static int simpledrm_probe(struct platform_device *pdev)
  {
  	struct simpledrm_device *sdev;
  	struct drm_device *dev;
+	unsigned int color_mode;
  	int ret;
  
  	sdev = simpledrm_device_create(&simpledrm_driver, pdev);
@@ -813,7 +814,11 @@ static int simpledrm_probe(struct platform_device *pdev)
  	if (ret)
  		return ret;
  
-	drm_fbdev_generic_setup(dev, drm_format_info_bpp(sdev->format, 0));
+	color_mode = drm_format_info_bpp(sdev->format, 0);
+	if (color_mode == 16)
+		color_mode = sdev->format->depth; // can be 15 or 16
+
+	drm_fbdev_generic_setup(dev, color_mode);
  
  	return 0;
  }






