1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
index 978782a77629..0facd823c552 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
@@ -157,6 +157,11 @@ static void mtk_ovl_layer_off(struct mtk_ddp_comp *comp, unsigned int idx)
 
 static unsigned int ovl_fmt_convert(struct mtk_disp_ovl *ovl, unsigned int fmt)
 {
+        /* The return value in switch "MEM_MODE_INPUT_FORMAT_XXX"
+         * is defined in mediatek HW data sheet.
+         * The alphabet order in XXX is no relation to data
+         * arrangement in memory.
+         */
         switch (fmt) {
         default:
         case DRM_FORMAT_RGB565: