drm: Check actual format for legacy pageflip.

With modifiers one can actually have different format_info structs
for the same format, which now matters for AMDGPU since we convert
implicit modifiers to explicit modifiers with multiple planes.

I checked other drivers and it doesn't look like they end up triggering
this case so I think this is safe to relax.

Signed-off-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Zhan Liu <zhan.liu@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Fixes: 816853f9dc40 ("drm/amd/display: Set new format info for converted metadata.")
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210110021142.28221-1-bas@basnieuwenhuizen.nl

diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index e623194..a0cb746 100644 (file)
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -1163,7 +1163,14 @@ retry:
        if (ret)
                goto out;
 
-       if (old_fb->format != fb->format) {
+       /*
+        * Only check the FOURCC format code, excluding modifiers. This is
+        * enough for all legacy drivers. Atomic drivers have their own
+        * checks in their ->atomic_check implementation, which will
+        * return -EINVAL if any hw or driver constraint is violated due
+        * to modifier changes.
+        */
+       if (old_fb->format->format != fb->format->format) {
                DRM_DEBUG_KMS("Page flip is not allowed to change frame buffer format.\n");
                ret = -EINVAL;
                goto out;