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-drm/kms.c#L431
[2] https://github.com/JoseExposito/drm-sandbox/blob/main/in_formats.c
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Reviewed-by: Simon Ser <contact@emersion.fr>
Signed-off-by: Simon Ser <contact@emersion.fr>
Link: https://patchwork.freedesktop.org/patch/msgid/20211226112503.31771-2-jose.exposito89@gmail.com
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])) {
-
mod->formats |= 1ULL << j;
}
}
mod++;
}
-done:
drm_object_attach_property(&plane->base, config->modifiers_property,
blob->base.id);