diff --git a/drivers/gpu/drm/rockchip/cdn-dp-reg.c b/drivers/gpu/drm/rockchip/cdn-dp-reg.c
index 5a485489a1e23cca8b3c455d368d42320140774e..6c8b14fb1d2f3c11ddefff385bff3a070f99ba3b 100644
--- a/drivers/gpu/drm/rockchip/cdn-dp-reg.c
+++ b/drivers/gpu/drm/rockchip/cdn-dp-reg.c
@@ -113,7 +113,7 @@ static int cdp_dp_mailbox_write(struct cdn_dp_device *dp, u8 val)
 
 static int cdn_dp_mailbox_validate_receive(struct cdn_dp_device *dp,
 					   u8 module_id, u8 opcode,
-					   u8 req_size)
+					   u16 req_size)
 {
 	u32 mbox_size, i;
 	u8 header[4];