drm: rockchip: hdmi: check sink max_tmds_clock in mode_valid

If sink max TMDS clock < 340MHz, we think the mode pixel clock
greater than 340MHz should support YCbCr420, or it is a bad mode.

Change-Id: I9f53fa4f9875977ae0355b65d9ccd8a304558c5d
Signed-off-by: Zheng Yang <zhengyang@rock-chips.com>

Author: Zheng Yang

drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c

@@ -888,6 +888,14 @@ dw_hdmi_rockchip_mode_valid(struct drm_connector *connector,
 	 */
 	if (mode->clock > INT_MAX / 1000)
 		return MODE_BAD;
+	/*
+	 * If sink max TMDS clock < 340MHz, we should check the mode pixel
+	 * clock > 340MHz is YCbCr420 or not.
+	 */
+	if (mode->clock > 340000 &&
+	    connector->display_info.max_tmds_clock < 340000 &&
+	    !(mode->flags & DRM_MODE_FLAG_420_MASK))
+		return MODE_BAD;
 
 	if (!encoder) {
 		const struct drm_connector_helper_funcs *funcs;