drm: bridge/dw_hdmi: enable audio only if sink supports audio

Only enable audio support if the sink supports audio in some form, as
defined via its EDID.  We discover this capability using the generic
drm_detect_monitor_audio() function.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/gpu/drm/bridge/dw_hdmi.c

@@ -123,6 +123,7 @@ struct dw_hdmi {
 	struct i2c_adapter *ddc;
 	void __iomem *regs;
 	bool sink_is_hdmi;
+	bool sink_has_audio;
 
 	spinlock_t audio_lock;
 	struct mutex audio_mutex;
@@ -1257,13 +1258,17 @@ static int dw_hdmi_setup(struct dw_hdmi *hdmi, struct drm_display_mode *mode)
 	/* HDMI Initialization Step B.3 */
 	dw_hdmi_enable_video_path(hdmi);
 
-	/* not for DVI mode */
-	if (hdmi->sink_is_hdmi) {
-		dev_dbg(hdmi->dev, "%s HDMI mode\n", __func__);
+	if (hdmi->sink_has_audio) {
+		dev_dbg(hdmi->dev, "sink has audio support\n");
 
 		/* HDMI Initialization Step E - Configure audio */
 		hdmi_clk_regenerator_update_pixel_clock(hdmi);
 		hdmi_enable_audio_clk(hdmi);
+	}
+
+	/* not for DVI mode */
+	if (hdmi->sink_is_hdmi) {
+		dev_dbg(hdmi->dev, "%s HDMI mode\n", __func__);
 
 		/* HDMI Initialization Step F - Configure AVI InfoFrame */
 		hdmi_config_AVI(hdmi, mode);
@@ -1428,6 +1433,7 @@ static int dw_hdmi_connector_get_modes(struct drm_connector *connector)
 			edid->width_cm, edid->height_cm);
 
 		hdmi->sink_is_hdmi = drm_detect_hdmi_monitor(edid);
+		hdmi->sink_has_audio = drm_detect_monitor_audio(edid);
 		drm_mode_connector_update_edid_property(connector, edid);
 		ret = drm_add_edid_modes(connector, edid);
 		kfree(edid);