As the function uses non-trivial bit operations, add a little paragraph to describe what is the expected behavior. Signed-off-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx> --- drivers/gpu/drm/drm_blend.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c index 6e74de833466..8d4b317eb9d7 100644 --- a/drivers/gpu/drm/drm_blend.c +++ b/drivers/gpu/drm/drm_blend.c @@ -321,6 +321,11 @@ EXPORT_SYMBOL(drm_plane_create_rotation_property); * transforms the hardware supports, this function may not * be able to produce a supported transform, so the caller should * check the result afterwards. + * + * If the rotation is not fully supported, this function will add a rotation of 180 + * (ROTATE_90 would become ROTATE_270) and add a reflection on X and Y. + * The resulting transformation is the same (REFLECT_X | REFLECT_Y | ROTATE_180 + * is a no-op), but some unsupported flags are removed. */ unsigned int drm_rotation_simplify(unsigned int rotation, unsigned int supported_rotations) -- 2.43.0
