drm/fb-helper: Replace bpp/depth parameter by color mode

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@suse.de>
Tested-by: Maíra Canal <mcanal@igalia.com> # vc4 and vkms
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Fixes: 37c90d589dc0 ("drm/fb-helper: Fix single-probe color-format selection")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230106112324.22055-1-tzimmermann@suse.de

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 1369ca4..4276317 100644 (file)
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1756,24 +1756,21 @@ err:
        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 39c5fd4..6e349ca 100644 (file)
--- 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 7355617..f658b99 100644 (file)
--- 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;
 }