drm: Trust format_mod_supported() when it OKs a plane modifier.

For parameterized modifiers (Broadcom's SAND and UIF), we need to
allow the parameter fields to be filled in, while exposing only the
variant of the modifier with the parameter unfilled in the internal
arrays and the format blob.

Signed-off-by: Eric Anholt <eric@anholt.net>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180316220435.31416-1-eric@anholt.net
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
index 26fa50c2a50e..14b1607aba4b 100644
--- a/include/drm/drm_plane.h
+++ b/include/drm/drm_plane.h
@@ -431,7 +431,10 @@ struct drm_plane_funcs {
 	 * 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).
+	 * which modifier), and to valdiate 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.
 	 *
 	 * Returns:
 	 *