On Wed, Mar 24, 2021 at 8:10 AM Daniel Stone <daniel@xxxxxxxxxxxxx> wrote: > > On Wed, 24 Mar 2021 at 10:53, Bas Nieuwenhuizen <bas@xxxxxxxxxxxxxxxxxxx> wrote: >> >> On Wed, Mar 24, 2021 at 11:13 AM Michel Dänzer <michel@xxxxxxxxxxx> wrote: >>> >>> No modifier support does not imply linear. It's generally signalled via DRM_FORMAT_MOD_INVALID, which roughly means "tiling is determined by driver specific mechanisms". So you mean it would make more sense to be more explicit in handling DRM_FORMAT_MOD_INVALID as an incoming modifier (which will, just like DRM_FORMAT_MOD_LINEAR, will return true in dm_plane_format_mod_supported)? >> >> >> Doesn't quite work that way in the kernel sadly. If you don't set DRM_MODE_FB_MODIFIERS then the modifier fields have to be 0 (which happens to alias DRM_FORMAT_MOD_LINEAR and then now deprecated DRM_FORMAT_MOD_NONE). This is verified in shared drm code. >> >> (and all userspace code I've seen simply doesn't set DRM_MODE_FB_MODIFIERS if the incoming modifier is DRM_FORMAT_MOD_INVALID) > > > Yes, but even though the field is zero, the lack of the flag means it must be treated as INVALID. If the kernel is not doing this, the kernel is objectively wrong. (And I know it doesn't do this in most cases, because otherwise I wouldn't be able to use this GNOME session on an Intel laptop, where modifiers are blacklisted.) > > Cheers, > Daniel _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
