drm/dp: add helper for checking DP_ENHANCED_FRAME_CAP in DPCD

Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

include/drm/drm_dp_helper.h

@@ -390,4 +390,11 @@ drm_dp_max_lane_count(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
 	return dpcd[DP_MAX_LANE_COUNT] & DP_MAX_LANE_COUNT_MASK;
 }
 
+static inline bool
+drm_dp_enhanced_frame_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	return dpcd[DP_DPCD_REV] >= 0x11 &&
+		(dpcd[DP_MAX_LANE_COUNT] & DP_ENHANCED_FRAME_CAP);
+}
+
 #endif /* _DRM_DP_HELPER_H_ */