drm/client: Restrict the rotation check to the rotation itself

The drm_client_rotation has a check on the rotation value, but the
reflections are also stored in the same variable, and the check doesn't
take this into account.

Therefore, even though we might have a valid rotation, if we're also using
a reflection parameter, the test will fail for no particular reason.
Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/cf4de0cdef20aac6c654b7b73c2ab3e317c46803.1560783090.git-series.maxime.ripard@bootlin.com

drivers/gpu/drm/drm_client_modeset.c

@@ -845,7 +845,8 @@ bool drm_client_panel_rotation(struct drm_mode_set *modeset, unsigned int *rotat
 	 * depending on the hardware this may require the framebuffer
 	 * to be in a specific tiling format.
 	 */
-	if (*rotation != DRM_MODE_ROTATE_180 || !plane->rotation_property)
+	if ((*rotation & DRM_MODE_ROTATE_MASK) != DRM_MODE_ROTATE_180 ||
+	    !plane->rotation_property)
 		return false;
 
 	for (i = 0; i < plane->rotation_property->num_values; i++)