drm/bridge: split HDMI Audio from DRM_BRIDGE_OP_HDMI

As pointed out by Laurent, OP bits are supposed to describe operations.
Split DRM_BRIDGE_OP_HDMI_AUDIO from DRM_BRIDGE_OP_HDMI instead of
overloading DRM_BRIDGE_OP_HDMI.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250314-dp-hdmi-audio-v6-1-dbd228fa73d7@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

drivers/gpu/drm/bridge/lontium-lt9611.c

@@ -1131,7 +1131,7 @@ static int lt9611_probe(struct i2c_client *client)
 	lt9611->bridge.of_node = client->dev.of_node;
 	lt9611->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID |
 			     DRM_BRIDGE_OP_HPD | DRM_BRIDGE_OP_MODES |
-			     DRM_BRIDGE_OP_HDMI;
+			     DRM_BRIDGE_OP_HDMI | DRM_BRIDGE_OP_HDMI_AUDIO;
 	lt9611->bridge.type = DRM_MODE_CONNECTOR_HDMIA;
 	lt9611->bridge.vendor = "Lontium";
 	lt9611->bridge.product = "LT9611";

drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c

@@ -1077,6 +1077,7 @@ struct dw_hdmi_qp *dw_hdmi_qp_bind(struct platform_device *pdev,
 	hdmi->bridge.ops = DRM_BRIDGE_OP_DETECT |
 			   DRM_BRIDGE_OP_EDID |
 			   DRM_BRIDGE_OP_HDMI |
+			   DRM_BRIDGE_OP_HDMI_AUDIO |
 			   DRM_BRIDGE_OP_HPD;
 	hdmi->bridge.of_node = pdev->dev.of_node;
 	hdmi->bridge.type = DRM_MODE_CONNECTOR_HDMIA;

drivers/gpu/drm/display/drm_bridge_connector.c

@@ -98,6 +98,13 @@ struct drm_bridge_connector {
 	 * HDMI connector infrastructure, if any (see &DRM_BRIDGE_OP_HDMI).
 	 */
 	struct drm_bridge *bridge_hdmi;
+	/**
+	 * @bridge_hdmi_audio:
+	 *
+	 * The bridge in the chain that implements necessary support for the
+	 * HDMI Audio infrastructure, if any (see &DRM_BRIDGE_OP_HDMI_AUDIO).
+	 */
+	struct drm_bridge *bridge_hdmi_audio;
 };
 
 #define to_drm_bridge_connector(x) \
@@ -433,7 +440,7 @@ 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;
+	bridge = bridge_connector->bridge_hdmi_audio;
 	if (!bridge)
 		return -EINVAL;
 
@@ -451,7 +458,7 @@ 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;
+	bridge = bridge_connector->bridge_hdmi_audio;
 	if (!bridge)
 		return -EINVAL;
 
@@ -464,7 +471,7 @@ 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;
+	bridge = bridge_connector->bridge_hdmi_audio;
 	if (!bridge)
 		return;
 
@@ -478,7 +485,7 @@ 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;
+	bridge = bridge_connector->bridge_hdmi_audio;
 	if (!bridge)
 		return -EINVAL;
 
@@ -576,6 +583,21 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 				max_bpc = bridge->max_bpc;
 		}
 
+		if (bridge->ops & DRM_BRIDGE_OP_HDMI_AUDIO) {
+			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->hdmi_audio_prepare ||
+			    !bridge->funcs->hdmi_audio_shutdown)
+				return ERR_PTR(-EINVAL);
+
+			bridge_connector->bridge_hdmi_audio = bridge;
+		}
+
 		if (!drm_bridge_get_next_bridge(bridge))
 			connector_type = bridge->type;
 
@@ -611,22 +633,6 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 					       max_bpc);
 		if (ret)
 			return ERR_PTR(ret);
-
-		if (bridge->hdmi_audio_max_i2s_playback_channels ||
-		    bridge->hdmi_audio_spdif_playback) {
-			if (!bridge->funcs->hdmi_audio_prepare ||
-			    !bridge->funcs->hdmi_audio_shutdown)
-				return ERR_PTR(-EINVAL);
-
-			ret = drm_connector_hdmi_audio_init(connector,
-							    bridge->hdmi_audio_dev,
-							    &drm_bridge_connector_hdmi_audio_funcs,
-							    bridge->hdmi_audio_max_i2s_playback_channels,
-							    bridge->hdmi_audio_spdif_playback,
-							    bridge->hdmi_audio_dai_port);
-			if (ret)
-				return ERR_PTR(ret);
-		}
 	} else {
 		ret = drmm_connector_init(drm, connector,
 					  &drm_bridge_connector_funcs,
@@ -635,6 +641,19 @@ 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;
+
+		ret = drm_connector_hdmi_audio_init(connector,
+						    bridge->hdmi_audio_dev,
+						    &drm_bridge_connector_hdmi_audio_funcs,
+						    bridge->hdmi_audio_max_i2s_playback_channels,
+						    bridge->hdmi_audio_spdif_playback,
+						    bridge->hdmi_audio_dai_port);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+
 	drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
 
 	if (bridge_connector->bridge_hpd)

drivers/gpu/drm/msm/hdmi/hdmi_bridge.c

@@ -515,6 +515,7 @@ int msm_hdmi_bridge_init(struct hdmi *hdmi)
 	bridge->ops = DRM_BRIDGE_OP_HPD |
 		DRM_BRIDGE_OP_DETECT |
 		DRM_BRIDGE_OP_HDMI |
+		DRM_BRIDGE_OP_HDMI_AUDIO |
 		DRM_BRIDGE_OP_EDID;
 	bridge->hdmi_audio_max_i2s_playback_channels = 8;
 	bridge->hdmi_audio_dev = &hdmi->pdev->dev;

include/drm/drm_bridge.h

@@ -681,8 +681,10 @@ struct drm_bridge_funcs {
 	/**
 	 * @hdmi_audio_startup:
 	 *
-	 * Called when ASoC starts an audio stream setup. The
+	 * Called when ASoC starts an audio stream setup.
-	 * @hdmi_audio_startup() is optional.
+	 *
+	 * This callback is optional, it can be implemented by bridges that
+	 * set the @DRM_BRIDGE_OP_HDMI_AUDIO flag in their &drm_bridge->ops.
 	 *
 	 * Returns:
 	 * 0 on success, a negative error code otherwise
@@ -693,8 +695,10 @@ struct drm_bridge_funcs {
 	/**
 	 * @hdmi_audio_prepare:
 	 * Configures HDMI-encoder for audio stream. Can be called multiple
-	 * times for each setup. Mandatory if HDMI audio is enabled in the
+	 * times for each setup.
-	 * bridge's configuration.
+	 *
+	 * This callback is optional but it must be implemented by bridges that
+	 * set the @DRM_BRIDGE_OP_HDMI_AUDIO flag in their &drm_bridge->ops.
 	 *
 	 * Returns:
 	 * 0 on success, a negative error code otherwise
@@ -707,8 +711,10 @@ struct drm_bridge_funcs {
 	/**
 	 * @hdmi_audio_shutdown:
 	 *
-	 * Shut down the audio stream. Mandatory if HDMI audio is enabled in
+	 * Shut down the audio stream.
-	 * the bridge's configuration.
+	 *
+	 * This callback is optional but it must be implemented by bridges that
+	 * set the @DRM_BRIDGE_OP_HDMI_AUDIO flag in their &drm_bridge->ops.
 	 *
 	 * Returns:
 	 * 0 on success, a negative error code otherwise
@@ -719,8 +725,10 @@ struct drm_bridge_funcs {
 	/**
 	 * @hdmi_audio_mute_stream:
 	 *
-	 * Mute/unmute HDMI audio stream. The @hdmi_audio_mute_stream callback
+	 * Mute/unmute HDMI audio stream.
-	 * is optional.
+	 *
+	 * This callback is optional, it can be implemented by bridges that
+	 * set the @DRM_BRIDGE_OP_HDMI_AUDIO flag in their &drm_bridge->ops.
 	 *
 	 * Returns:
 	 * 0 on success, a negative error code otherwise
@@ -814,6 +822,17 @@ enum drm_bridge_ops {
 	 * drivers.
 	 */
 	DRM_BRIDGE_OP_HDMI = BIT(4),
+	/**
+	 * @DRM_BRIDGE_OP_HDMI_AUDIO: The bridge provides HDMI audio operations.
+	 * Bridges that set this flag must implement the
+	 * &drm_bridge_funcs->hdmi_audio_prepare and
+	 * &drm_bridge_funcs->hdmi_audio_shutdown callbacks.
+	 *
+	 * Note: currently there can be at most one bridge in a chain that sets
+	 * this bit. This is to simplify corresponding glue code in connector
+	 * drivers.
+	 */
+	DRM_BRIDGE_OP_HDMI_AUDIO = BIT(5),
 };
 
 /**
@@ -926,23 +945,26 @@ struct drm_bridge {
 	unsigned int max_bpc;
 
 	/**
-	 * @hdmi_audio_dev: device to be used as a parent for the HDMI Codec
+	 * @hdmi_audio_dev: device to be used as a parent for the HDMI Codec if
+	 * @DRM_BRIDGE_OP_HDMI_AUDIO is set.
 	 */
 	struct device *hdmi_audio_dev;
 
 	/**
 	 * @hdmi_audio_max_i2s_playback_channels: maximum number of playback
-	 * I2S channels for the HDMI codec
+	 * I2S channels for the bridge that sets @DRM_BRIDGE_OP_HDMI_AUDIO.
 	 */
 	int hdmi_audio_max_i2s_playback_channels;
 
 	/**
-	 * @hdmi_audio_spdif_playback: set if HDMI codec has S/PDIF playback port
+	 * @hdmi_audio_spdif_playback: set if this bridge has S/PDIF playback
+	 * port for @DRM_BRIDGE_OP_HDMI_AUDIO
 	 */
 	unsigned int hdmi_audio_spdif_playback : 1;
 
 	/**
-	 * @hdmi_audio_dai_port: sound DAI port, -1 if it is not enabled
+	 * @hdmi_audio_dai_port: sound DAI port for @DRM_BRIDGE_OP_HDMI_AUDIO,
+	 * -1 if it is not used.
 	 */
 	int hdmi_audio_dai_port;
 };