drm/bridge-connector: hook DisplayPort audio support

Reuse existing code plumbing HDMI audio support and the existing HDMI
audio helpers that register HDMI codec device and plumb in the
DisplayPort audio interfaces to be handled by the drm_bridge_connector.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250314-dp-hdmi-audio-v6-3-dbd228fa73d7@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

Author: lumag

drivers/gpu/drm/display/drm_bridge_connector.c

@@ -105,6 +105,14 @@ struct drm_bridge_connector {
 	 * HDMI Audio infrastructure, if any (see &DRM_BRIDGE_OP_HDMI_AUDIO).
 	 */
 	struct drm_bridge *bridge_hdmi_audio;
+	/**
+	 * @bridge_dp_audio:
+	 *
+	 * The bridge in the chain that implements necessary support for the
+	 * DisplayPort Audio infrastructure, if any (see
+	 * &DRM_BRIDGE_OP_DP_AUDIO).
+	 */
+	struct drm_bridge *bridge_dp_audio;
 };
 
 #define to_drm_bridge_connector(x) \
@@ -440,14 +448,25 @@ static int drm_bridge_connector_audio_startup(struct drm_connector *connector)
 		to_drm_bridge_connector(connector);
 	struct drm_bridge *bridge;
 
-	bridge = bridge_connector->bridge_hdmi_audio;
-	if (!bridge)
-		return -EINVAL;
+	if (bridge_connector->bridge_hdmi_audio) {
+		bridge = bridge_connector->bridge_hdmi_audio;
 
-	if (!bridge->funcs->hdmi_audio_startup)
-		return 0;
+		if (!bridge->funcs->hdmi_audio_startup)
+			return 0;
 
-	return bridge->funcs->hdmi_audio_startup(connector, bridge);
+		return bridge->funcs->hdmi_audio_startup(connector, bridge);
+	}
+
+	if (bridge_connector->bridge_dp_audio) {
+		bridge = bridge_connector->bridge_dp_audio;
+
+		if (!bridge->funcs->dp_audio_startup)
+			return 0;
+
+		return bridge->funcs->dp_audio_startup(connector, bridge);
+	}
+
+	return -EINVAL;
 }
 
 static int drm_bridge_connector_audio_prepare(struct drm_connector *connector,
@@ -458,11 +477,19 @@ static int drm_bridge_connector_audio_prepare(struct drm_connector *connector,
 		to_drm_bridge_connector(connector);
 	struct drm_bridge *bridge;
 
-	bridge = bridge_connector->bridge_hdmi_audio;
-	if (!bridge)
-		return -EINVAL;
+	if (bridge_connector->bridge_hdmi_audio) {
+		bridge = bridge_connector->bridge_hdmi_audio;
+
+		return bridge->funcs->hdmi_audio_prepare(connector, bridge, fmt, hparms);
+	}
+
+	if (bridge_connector->bridge_dp_audio) {
+		bridge = bridge_connector->bridge_dp_audio;
+
+		return bridge->funcs->dp_audio_prepare(connector, bridge, fmt, hparms);
+	}
 
-	return bridge->funcs->hdmi_audio_prepare(connector, bridge, fmt, hparms);
+	return -EINVAL;
 }
 
 static void drm_bridge_connector_audio_shutdown(struct drm_connector *connector)
@@ -471,11 +498,15 @@ static void drm_bridge_connector_audio_shutdown(struct drm_connector *connector)
 		to_drm_bridge_connector(connector);
 	struct drm_bridge *bridge;
 
-	bridge = bridge_connector->bridge_hdmi_audio;
-	if (!bridge)
-		return;
+	if (bridge_connector->bridge_hdmi_audio) {
+		bridge = bridge_connector->bridge_hdmi_audio;
+		bridge->funcs->hdmi_audio_shutdown(connector, bridge);
+	}
 
-	bridge->funcs->hdmi_audio_shutdown(connector, bridge);
+	if (bridge_connector->bridge_dp_audio) {
+		bridge = bridge_connector->bridge_dp_audio;
+		bridge->funcs->dp_audio_shutdown(connector, bridge);
+	}
 }
 
 static int drm_bridge_connector_audio_mute_stream(struct drm_connector *connector,
@@ -485,15 +516,27 @@ static int drm_bridge_connector_audio_mute_stream(struct drm_connector *connecto
 		to_drm_bridge_connector(connector);
 	struct drm_bridge *bridge;
 
-	bridge = bridge_connector->bridge_hdmi_audio;
-	if (!bridge)
-		return -EINVAL;
+	if (bridge_connector->bridge_hdmi_audio) {
+		bridge = bridge_connector->bridge_hdmi_audio;
+
+		if (!bridge->funcs->hdmi_audio_mute_stream)
+			return -ENOTSUPP;
 
-	if (bridge->funcs->hdmi_audio_mute_stream)
 		return bridge->funcs->hdmi_audio_mute_stream(connector, bridge,
 							     enable, direction);
-	else
-		return -ENOTSUPP;
+	}
+
+	if (bridge_connector->bridge_dp_audio) {
+		bridge = bridge_connector->bridge_dp_audio;
+
+		if (!bridge->funcs->dp_audio_mute_stream)
+			return -ENOTSUPP;
+
+		return bridge->funcs->dp_audio_mute_stream(connector, bridge,
+							   enable, direction);
+	}
+
+	return -EINVAL;
 }
 
 static const struct drm_connector_hdmi_audio_funcs drm_bridge_connector_hdmi_audio_funcs = {
@@ -587,6 +630,9 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 			if (bridge_connector->bridge_hdmi_audio)
 				return ERR_PTR(-EBUSY);
 
+			if (bridge_connector->bridge_dp_audio)
+				return ERR_PTR(-EBUSY);
+
 			if (!bridge->hdmi_audio_max_i2s_playback_channels &&
 			    !bridge->hdmi_audio_spdif_playback)
 				return ERR_PTR(-EINVAL);
@@ -598,6 +644,24 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 			bridge_connector->bridge_hdmi_audio = bridge;
 		}
 
+		if (bridge->ops & DRM_BRIDGE_OP_DP_AUDIO) {
+			if (bridge_connector->bridge_dp_audio)
+				return ERR_PTR(-EBUSY);
+
+			if (bridge_connector->bridge_hdmi_audio)
+				return ERR_PTR(-EBUSY);
+
+			if (!bridge->hdmi_audio_max_i2s_playback_channels &&
+			    !bridge->hdmi_audio_spdif_playback)
+				return ERR_PTR(-EINVAL);
+
+			if (!bridge->funcs->dp_audio_prepare ||
+			    !bridge->funcs->dp_audio_shutdown)
+				return ERR_PTR(-EINVAL);
+
+			bridge_connector->bridge_dp_audio = bridge;
+		}
+
 		if (!drm_bridge_get_next_bridge(bridge))
 			connector_type = bridge->type;
 
@@ -641,11 +705,16 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 			return ERR_PTR(ret);
 	}
 
-	if (bridge_connector->bridge_hdmi_audio) {
-		bridge = bridge_connector->bridge_hdmi_audio;
+	if (bridge_connector->bridge_hdmi_audio ||
+	    bridge_connector->bridge_dp_audio) {
+		struct device *dev;
+
+		if (bridge_connector->bridge_hdmi_audio)
+			dev = bridge_connector->bridge_hdmi_audio->hdmi_audio_dev;
+		else
+			dev = bridge_connector->bridge_dp_audio->hdmi_audio_dev;
 
-		ret = drm_connector_hdmi_audio_init(connector,
-						    bridge->hdmi_audio_dev,
+		ret = drm_connector_hdmi_audio_init(connector, dev,
 						    &drm_bridge_connector_hdmi_audio_funcs,
 						    bridge->hdmi_audio_max_i2s_playback_channels,
 						    bridge->hdmi_audio_spdif_playback,