Emphasize how userspace should use the plane format list (format_type_ptr) and the IN_FORMATS blob property.
Formats exposed in the plane format list (format_type_ptr) do not require modifiers, and formats that are present in the IN_FORMATS blob property support modifiers.
Note that these are not disjoint sets. If a format supports modifiers but the driver can also handle it without a modifier, it should be present in both the IN_FORMATS blob property and the plane format list.
Signed-off-by: Leandro Ribeiro leandro.ribeiro@collabora.com --- drivers/gpu/drm/drm_plane.c | 4 ++++ include/uapi/drm/drm_mode.h | 3 +++ 2 files changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c index 0dd43882fe7c..b48d9bd81a59 100644 --- a/drivers/gpu/drm/drm_plane.c +++ b/drivers/gpu/drm/drm_plane.c @@ -128,6 +128,10 @@ * pairs supported by this plane. The blob is a struct * drm_format_modifier_blob. Without this property the plane doesn't * support buffers with modifiers. Userspace cannot change this property. + * + * To find out the list of buffer formats which are supported without a + * modifier, userspace should not look at this blob property, but at the + * formats list of the plane: &drm_mode_get_plane.format_type_ptr. */
static unsigned int drm_num_planes(struct drm_device *dev) diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h index 96fc9a6da608..4293800ec095 100644 --- a/include/uapi/drm/drm_mode.h +++ b/include/uapi/drm/drm_mode.h @@ -340,6 +340,9 @@ struct drm_mode_get_plane { /** * @format_type_ptr: Pointer to ``__u32`` array of formats that are * supported by the plane. These formats do not require modifiers. + * + * To find out the list of formats that support modifiers, userspace + * must use the plane IN_FORMATS blob property. */ __u64 format_type_ptr; };