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-drm/kms.c#L431 > [2] https://github.com/JoseExposito/drm-sandbox/blob/main/in_formats.c > > Signed-off-by: José Expósito <jose.exposito89@xxxxxxxxx> > --- > 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. -- Ville Syrjälä Intel
