On Wed, Dec 22, 2021 at 10:05:47AM +0100, José Expósito wrote:
The documentation for "drm_plane_funcs.format_mod_supported" reads:
This *optional* hook is used for the DRM to determine if the given format/modifier combination is valid for the plane. This allows the DRM to generate the correct format bitmask (which formats apply to which modifier), and to validate modifiers at atomic_check time.
*If not present*, then any modifier in the plane's modifier list is allowed with any of the plane's formats.
However, where the function is not present, an invalid IN_FORMATS blob property with modifiers but no formats is exposed to user-space.
This breaks the latest Weston [1]. For testing purposes, I extracted the affected code to a standalone program [2].
Make "create_in_format_blob" behave as documented.
[1] https://gitlab.freedesktop.org/wayland/weston/-/blob/9.0/libweston/backend-d... [2] https://github.com/JoseExposito/drm-sandbox/blob/main/in_formats.c
Signed-off-by: José Expósito jose.exposito89@gmail.com
drivers/gpu/drm/drm_plane.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c index 82afb854141b..c1186b7215ee 100644 --- a/drivers/gpu/drm/drm_plane.c +++ b/drivers/gpu/drm/drm_plane.c @@ -202,17 +202,13 @@ static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane
memcpy(formats_ptr(blob_data), plane->format_types, formats_size);
- /* If we can't determine support, just bail */
- if (!plane->funcs->format_mod_supported)
goto done;- mod = modifiers_ptr(blob_data); for (i = 0; i < plane->modifier_count; i++) { for (j = 0; j < plane->format_count; j++) {
if (plane->funcs->format_mod_supported(plane,
if (!plane->funcs->format_mod_supported ||plane->funcs->format_mod_supported(plane, plane->format_types[j], plane->modifiers[i])) {
So instead of skipping the whole loop you just skip doing anything inside the loop? Can't see how that achieves anything at all.
https://patchwork.freedesktop.org/series/83018/ is what I had in mind earlier but no one reviewed it and the discussion veered off track IIRC.