DRM HDMI Codec framework is useful not only for the HDMI bridges, but
also for the DisplayPort bridges. Add new DRM_BRIDGE_OP_DisplayPort
define in order to distinguish DP bridges. Create HDMI codec device
automatically for DP bridges which have declared audio support.

Note, unlike HDMI devices, which already have a framework to handle HPD
notifications in a standard way, DP drivers don't (yet?) have such a
framework. As such it is necessary to manually call
drm_connector_hdmi_audio_plugged_notify(). This requirement hopefully
can be lifted later on, if/when DRM framework gets better DisplayPort
ports support in the core layer.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/display/drm_bridge_connector.c | 66 ++++++++++++++++++++------
 include/drm/drm_bridge.h                       | 14 +++++-
 2 files changed, 65 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
index 30c736fc0067e31a97db242e5b16ea8a5b4cf359..5e031395b801f9a1371dcb4ac09f3da23e4615dd 100644
--- a/drivers/gpu/drm/display/drm_bridge_connector.c
+++ b/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_dp:
+	 *
+	 * The bridge in the chain that implements necessary support for the
+	 * DisplayPort connector infrastructure, if any (see &DRM_BRIDGE_OP_DisplayPort).
+	 */
+	struct drm_bridge *bridge_dp;
 };
 
 #define to_drm_bridge_connector(x) \
@@ -496,6 +503,25 @@ static const struct drm_connector_hdmi_audio_funcs drm_bridge_connector_hdmi_aud
 	.mute_stream = drm_bridge_connector_audio_mute_stream,
 };
 
+static int drm_bridge_connector_hdmi_audio_init(struct drm_connector *connector,
+						struct drm_bridge *bridge)
+{
+	if (!bridge->hdmi_audio_max_i2s_playback_channels &&
+	    !bridge->hdmi_audio_spdif_playback)
+		return 0;
+
+	if (!bridge->funcs->hdmi_audio_prepare ||
+	    !bridge->funcs->hdmi_audio_shutdown)
+		return -EINVAL;
+
+	return 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);
+}
+
 /* -----------------------------------------------------------------------------
  * Bridge Connector Initialisation
  */
@@ -564,6 +590,8 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 		if (bridge->ops & DRM_BRIDGE_OP_HDMI) {
 			if (bridge_connector->bridge_hdmi)
 				return ERR_PTR(-EBUSY);
+			if (bridge_connector->bridge_dp)
+				return ERR_PTR(-EINVAL);
 			if (!bridge->funcs->hdmi_write_infoframe ||
 			    !bridge->funcs->hdmi_clear_infoframe)
 				return ERR_PTR(-EINVAL);
@@ -576,6 +604,16 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 				max_bpc = bridge->max_bpc;
 		}
 
+		if (bridge->ops & DRM_BRIDGE_OP_DisplayPort) {
+			if (bridge_connector->bridge_dp)
+				return ERR_PTR(-EBUSY);
+			if (bridge_connector->bridge_hdmi)
+				return ERR_PTR(-EINVAL);
+
+			bridge_connector->bridge_dp = bridge;
+
+		}
+
 		if (!drm_bridge_get_next_bridge(bridge))
 			connector_type = bridge->type;
 
@@ -612,21 +650,21 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 		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_bridge_connector_hdmi_audio_init(connector, bridge);
+		if (ret)
+			return ERR_PTR(ret);
+	} else if (bridge_connector->bridge_dp) {
+		bridge = bridge_connector->bridge_dp;
 
-			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);
-		}
+		ret = drmm_connector_init(drm, connector,
+					  &drm_bridge_connector_funcs,
+					  connector_type, ddc);
+		if (ret)
+			return ERR_PTR(ret);
+
+		ret = drm_bridge_connector_hdmi_audio_init(connector, bridge);
+		if (ret)
+			return ERR_PTR(ret);
 	} else {
 		ret = drmm_connector_init(drm, connector,
 					  &drm_bridge_connector_funcs,
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 496dbbd2ad7edff7f091adfbe62de1e33ef0cf07..40f37444426b1b8ded25da9ba9e2963f18ad6267 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -811,9 +811,21 @@ enum drm_bridge_ops {
 	 *
 	 * 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.
+	 * drivers. Having both HDMI and DisplayPort bridges in the same bridge
+	 * chain is also not allowed.
 	 */
 	DRM_BRIDGE_OP_HDMI = BIT(4),
+	/**
+	 * @DRM_BRIDGE_OP_DisplayPort: The bridge provides DisplayPort connector
+	 * operations. Currently this is limited to the optional HDMI codec
+	 * support.
+	 *
+	 * 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. Having both HDMI and DisplayPort bridges in the same bridge
+	 * chain is also not allowed.
+	 */
+	DRM_BRIDGE_OP_DisplayPort = BIT(5),
 };
 
 /**

-- 
2.39.5

Hi Dmitry,

Thank you for the patch.

On Sun, Feb 09, 2025 at 03:41:18PM +0200, Dmitry Baryshkov wrote:
> DRM HDMI Codec framework is useful not only for the HDMI bridges, but
> also for the DisplayPort bridges. Add new DRM_BRIDGE_OP_DisplayPort
> define in order to distinguish DP bridges. Create HDMI codec device
> automatically for DP bridges which have declared audio support.
> 
> Note, unlike HDMI devices, which already have a framework to handle HPD
> notifications in a standard way, DP drivers don't (yet?) have such a
> framework. As such it is necessary to manually call
> drm_connector_hdmi_audio_plugged_notify(). This requirement hopefully
> can be lifted later on, if/when DRM framework gets better DisplayPort
> ports support in the core layer.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  drivers/gpu/drm/display/drm_bridge_connector.c | 66 ++++++++++++++++++++------
>  include/drm/drm_bridge.h                       | 14 +++++-
>  2 files changed, 65 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
> index 30c736fc0067e31a97db242e5b16ea8a5b4cf359..5e031395b801f9a1371dcb4ac09f3da23e4615dd 100644
> --- a/drivers/gpu/drm/display/drm_bridge_connector.c
> +++ b/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_dp:
> +	 *
> +	 * The bridge in the chain that implements necessary support for the
> +	 * DisplayPort connector infrastructure, if any (see &DRM_BRIDGE_OP_DisplayPort).
> +	 */
> +	struct drm_bridge *bridge_dp;
>  };
>  
>  #define to_drm_bridge_connector(x) \
> @@ -496,6 +503,25 @@ static const struct drm_connector_hdmi_audio_funcs drm_bridge_connector_hdmi_aud
>  	.mute_stream = drm_bridge_connector_audio_mute_stream,
>  };
>  
> +static int drm_bridge_connector_hdmi_audio_init(struct drm_connector *connector,
> +						struct drm_bridge *bridge)
> +{
> +	if (!bridge->hdmi_audio_max_i2s_playback_channels &&
> +	    !bridge->hdmi_audio_spdif_playback)
> +		return 0;
> +
> +	if (!bridge->funcs->hdmi_audio_prepare ||
> +	    !bridge->funcs->hdmi_audio_shutdown)
> +		return -EINVAL;
> +
> +	return 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);
> +}
> +
>  /* -----------------------------------------------------------------------------
>   * Bridge Connector Initialisation
>   */
> @@ -564,6 +590,8 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>  		if (bridge->ops & DRM_BRIDGE_OP_HDMI) {
>  			if (bridge_connector->bridge_hdmi)
>  				return ERR_PTR(-EBUSY);
> +			if (bridge_connector->bridge_dp)
> +				return ERR_PTR(-EINVAL);
>  			if (!bridge->funcs->hdmi_write_infoframe ||
>  			    !bridge->funcs->hdmi_clear_infoframe)
>  				return ERR_PTR(-EINVAL);
> @@ -576,6 +604,16 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>  				max_bpc = bridge->max_bpc;
>  		}
>  
> +		if (bridge->ops & DRM_BRIDGE_OP_DisplayPort) {
> +			if (bridge_connector->bridge_dp)
> +				return ERR_PTR(-EBUSY);
> +			if (bridge_connector->bridge_hdmi)
> +				return ERR_PTR(-EINVAL);
> +
> +			bridge_connector->bridge_dp = bridge;
> +
> +		}
> +
>  		if (!drm_bridge_get_next_bridge(bridge))
>  			connector_type = bridge->type;
>  
> @@ -612,21 +650,21 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>  		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_bridge_connector_hdmi_audio_init(connector, bridge);
> +		if (ret)
> +			return ERR_PTR(ret);
> +	} else if (bridge_connector->bridge_dp) {
> +		bridge = bridge_connector->bridge_dp;
>  
> -			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);
> -		}
> +		ret = drmm_connector_init(drm, connector,
> +					  &drm_bridge_connector_funcs,
> +					  connector_type, ddc);
> +		if (ret)
> +			return ERR_PTR(ret);
> +
> +		ret = drm_bridge_connector_hdmi_audio_init(connector, bridge);
> +		if (ret)
> +			return ERR_PTR(ret);
>  	} else {
>  		ret = drmm_connector_init(drm, connector,
>  					  &drm_bridge_connector_funcs,
> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> index 496dbbd2ad7edff7f091adfbe62de1e33ef0cf07..40f37444426b1b8ded25da9ba9e2963f18ad6267 100644
> --- a/include/drm/drm_bridge.h
> +++ b/include/drm/drm_bridge.h
> @@ -811,9 +811,21 @@ enum drm_bridge_ops {
>  	 *
>  	 * 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.
> +	 * drivers. Having both HDMI and DisplayPort bridges in the same bridge
> +	 * chain is also not allowed.
>  	 */
>  	DRM_BRIDGE_OP_HDMI = BIT(4),
> +	/**
> +	 * @DRM_BRIDGE_OP_DisplayPort: The bridge provides DisplayPort connector
> +	 * operations. Currently this is limited to the optional HDMI codec
> +	 * support.
> +	 *
> +	 * 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. Having both HDMI and DisplayPort bridges in the same bridge
> +	 * chain is also not allowed.
> +	 */
> +	DRM_BRIDGE_OP_DisplayPort = BIT(5),

The OP bits are not supposed to describe tbe type of bridge, but the
operations it implements. I see quite a bit of duplication between HDMI
and DisplayPort in this patch. Can we have a single bit named after the
feature that you want to support ? The bridge_hdmi and bridge_dp fields
should also be merged into a single one.

>  };
>  
>  /**
> 

-- 
Regards,

Laurent Pinchart

On Fri, Feb 14, 2025 at 01:57:45AM +0200, Laurent Pinchart wrote:
> Hi Dmitry,
> 
> Thank you for the patch.
> 
> On Sun, Feb 09, 2025 at 03:41:18PM +0200, Dmitry Baryshkov wrote:
> > DRM HDMI Codec framework is useful not only for the HDMI bridges, but
> > also for the DisplayPort bridges. Add new DRM_BRIDGE_OP_DisplayPort
> > define in order to distinguish DP bridges. Create HDMI codec device
> > automatically for DP bridges which have declared audio support.
> > 
> > Note, unlike HDMI devices, which already have a framework to handle HPD
> > notifications in a standard way, DP drivers don't (yet?) have such a
> > framework. As such it is necessary to manually call
> > drm_connector_hdmi_audio_plugged_notify(). This requirement hopefully
> > can be lifted later on, if/when DRM framework gets better DisplayPort
> > ports support in the core layer.
> > 
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > ---
> >  drivers/gpu/drm/display/drm_bridge_connector.c | 66 ++++++++++++++++++++------
> >  include/drm/drm_bridge.h                       | 14 +++++-
> >  2 files changed, 65 insertions(+), 15 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
> > index 30c736fc0067e31a97db242e5b16ea8a5b4cf359..5e031395b801f9a1371dcb4ac09f3da23e4615dd 100644
> > --- a/drivers/gpu/drm/display/drm_bridge_connector.c
> > +++ b/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_dp:
> > +	 *
> > +	 * The bridge in the chain that implements necessary support for the
> > +	 * DisplayPort connector infrastructure, if any (see &DRM_BRIDGE_OP_DisplayPort).
> > +	 */
> > +	struct drm_bridge *bridge_dp;
> >  };
> >  
> >  #define to_drm_bridge_connector(x) \
> > @@ -496,6 +503,25 @@ static const struct drm_connector_hdmi_audio_funcs drm_bridge_connector_hdmi_aud
> >  	.mute_stream = drm_bridge_connector_audio_mute_stream,
> >  };
> >  
> > +static int drm_bridge_connector_hdmi_audio_init(struct drm_connector *connector,
> > +						struct drm_bridge *bridge)
> > +{
> > +	if (!bridge->hdmi_audio_max_i2s_playback_channels &&
> > +	    !bridge->hdmi_audio_spdif_playback)
> > +		return 0;
> > +
> > +	if (!bridge->funcs->hdmi_audio_prepare ||
> > +	    !bridge->funcs->hdmi_audio_shutdown)
> > +		return -EINVAL;
> > +
> > +	return 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);
> > +}
> > +
> >  /* -----------------------------------------------------------------------------
> >   * Bridge Connector Initialisation
> >   */
> > @@ -564,6 +590,8 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
> >  		if (bridge->ops & DRM_BRIDGE_OP_HDMI) {
> >  			if (bridge_connector->bridge_hdmi)
> >  				return ERR_PTR(-EBUSY);
> > +			if (bridge_connector->bridge_dp)
> > +				return ERR_PTR(-EINVAL);
> >  			if (!bridge->funcs->hdmi_write_infoframe ||
> >  			    !bridge->funcs->hdmi_clear_infoframe)
> >  				return ERR_PTR(-EINVAL);
> > @@ -576,6 +604,16 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
> >  				max_bpc = bridge->max_bpc;
> >  		}
> >  
> > +		if (bridge->ops & DRM_BRIDGE_OP_DisplayPort) {
> > +			if (bridge_connector->bridge_dp)
> > +				return ERR_PTR(-EBUSY);
> > +			if (bridge_connector->bridge_hdmi)
> > +				return ERR_PTR(-EINVAL);
> > +
> > +			bridge_connector->bridge_dp = bridge;
> > +
> > +		}
> > +
> >  		if (!drm_bridge_get_next_bridge(bridge))
> >  			connector_type = bridge->type;
> >  
> > @@ -612,21 +650,21 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
> >  		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_bridge_connector_hdmi_audio_init(connector, bridge);
> > +		if (ret)
> > +			return ERR_PTR(ret);
> > +	} else if (bridge_connector->bridge_dp) {
> > +		bridge = bridge_connector->bridge_dp;
> >  
> > -			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);
> > -		}
> > +		ret = drmm_connector_init(drm, connector,
> > +					  &drm_bridge_connector_funcs,
> > +					  connector_type, ddc);
> > +		if (ret)
> > +			return ERR_PTR(ret);
> > +
> > +		ret = drm_bridge_connector_hdmi_audio_init(connector, bridge);
> > +		if (ret)
> > +			return ERR_PTR(ret);
> >  	} else {
> >  		ret = drmm_connector_init(drm, connector,
> >  					  &drm_bridge_connector_funcs,
> > diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> > index 496dbbd2ad7edff7f091adfbe62de1e33ef0cf07..40f37444426b1b8ded25da9ba9e2963f18ad6267 100644
> > --- a/include/drm/drm_bridge.h
> > +++ b/include/drm/drm_bridge.h
> > @@ -811,9 +811,21 @@ enum drm_bridge_ops {
> >  	 *
> >  	 * 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.
> > +	 * drivers. Having both HDMI and DisplayPort bridges in the same bridge
> > +	 * chain is also not allowed.
> >  	 */
> >  	DRM_BRIDGE_OP_HDMI = BIT(4),
> > +	/**
> > +	 * @DRM_BRIDGE_OP_DisplayPort: The bridge provides DisplayPort connector
> > +	 * operations. Currently this is limited to the optional HDMI codec
> > +	 * support.
> > +	 *
> > +	 * 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. Having both HDMI and DisplayPort bridges in the same bridge
> > +	 * chain is also not allowed.
> > +	 */
> > +	DRM_BRIDGE_OP_DisplayPort = BIT(5),
> 
> The OP bits are not supposed to describe tbe type of bridge, but the
> operations it implements. I see quite a bit of duplication between HDMI
> and DisplayPort in this patch. Can we have a single bit named after the
> feature that you want to support ? The bridge_hdmi and bridge_dp fields
> should also be merged into a single one.

In this case these ops actually describe the set of ops implemented by
the bridge. DRM_BRIDGE_OP_HDMI implements hdmi_tmds_char_rate_valid(),
hdmi_write_infoframe(), hdmi_clear_infoframe() and hdmi_audio_*()
callbacks. It is impossible to just use HDMI helpers for any
DRM_MODE_CONNECTOR_HDMIA bridge as they lack required callbacks.
At the same time it is perfectly legic to have a
DRM_MODE_CONNECTOR_HDMIA bridge which doesn't set DRM_BRIDGE_OP_HDMI:
this bridge chain will not use HDMI Connector / HDMI State helpers, but
it should be fine otherwise.

DRM_BRIDGE_OP_DisplayPort bridges currently implement hdmi_audio_*(),
but I have long-term plans for that set of ops.

It is not quite possible to merge bridge_hdmi and bridge_dp fields:
for bridges, which implement DRM_BRIDGE_OP_HDMI, drm_bridge_connector
call various drm_atomic_helper_connector_hdmi_*() functions. For
DisplayPort there is no corresponding functionality (yet).

-- 
With best wishes
Dmitry

On Fri, Feb 14, 2025 at 02:32:56AM +0200, Dmitry Baryshkov wrote:
> On Fri, Feb 14, 2025 at 01:57:45AM +0200, Laurent Pinchart wrote:
> > Hi Dmitry,
> > 
> > Thank you for the patch.
> > 
> > On Sun, Feb 09, 2025 at 03:41:18PM +0200, Dmitry Baryshkov wrote:
> > > DRM HDMI Codec framework is useful not only for the HDMI bridges, but
> > > also for the DisplayPort bridges. Add new DRM_BRIDGE_OP_DisplayPort
> > > define in order to distinguish DP bridges. Create HDMI codec device
> > > automatically for DP bridges which have declared audio support.
> > > 
> > > Note, unlike HDMI devices, which already have a framework to handle HPD
> > > notifications in a standard way, DP drivers don't (yet?) have such a
> > > framework. As such it is necessary to manually call
> > > drm_connector_hdmi_audio_plugged_notify(). This requirement hopefully
> > > can be lifted later on, if/when DRM framework gets better DisplayPort
> > > ports support in the core layer.
> > > 
> > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > > ---
> > >  drivers/gpu/drm/display/drm_bridge_connector.c | 66 ++++++++++++++++++++------
> > >  include/drm/drm_bridge.h                       | 14 +++++-
> > >  2 files changed, 65 insertions(+), 15 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
> > > index 30c736fc0067e31a97db242e5b16ea8a5b4cf359..5e031395b801f9a1371dcb4ac09f3da23e4615dd 100644
> > > --- a/drivers/gpu/drm/display/drm_bridge_connector.c
> > > +++ b/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_dp:
> > > +	 *
> > > +	 * The bridge in the chain that implements necessary support for the
> > > +	 * DisplayPort connector infrastructure, if any (see &DRM_BRIDGE_OP_DisplayPort).
> > > +	 */
> > > +	struct drm_bridge *bridge_dp;
> > >  };
> > >  
> > >  #define to_drm_bridge_connector(x) \
> > > @@ -496,6 +503,25 @@ static const struct drm_connector_hdmi_audio_funcs drm_bridge_connector_hdmi_aud
> > >  	.mute_stream = drm_bridge_connector_audio_mute_stream,
> > >  };
> > >  
> > > +static int drm_bridge_connector_hdmi_audio_init(struct drm_connector *connector,
> > > +						struct drm_bridge *bridge)
> > > +{
> > > +	if (!bridge->hdmi_audio_max_i2s_playback_channels &&
> > > +	    !bridge->hdmi_audio_spdif_playback)
> > > +		return 0;
> > > +
> > > +	if (!bridge->funcs->hdmi_audio_prepare ||
> > > +	    !bridge->funcs->hdmi_audio_shutdown)
> > > +		return -EINVAL;
> > > +
> > > +	return 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);
> > > +}
> > > +
> > >  /* -----------------------------------------------------------------------------
> > >   * Bridge Connector Initialisation
> > >   */
> > > @@ -564,6 +590,8 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
> > >  		if (bridge->ops & DRM_BRIDGE_OP_HDMI) {
> > >  			if (bridge_connector->bridge_hdmi)
> > >  				return ERR_PTR(-EBUSY);
> > > +			if (bridge_connector->bridge_dp)
> > > +				return ERR_PTR(-EINVAL);
> > >  			if (!bridge->funcs->hdmi_write_infoframe ||
> > >  			    !bridge->funcs->hdmi_clear_infoframe)
> > >  				return ERR_PTR(-EINVAL);
> > > @@ -576,6 +604,16 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
> > >  				max_bpc = bridge->max_bpc;
> > >  		}
> > >  
> > > +		if (bridge->ops & DRM_BRIDGE_OP_DisplayPort) {
> > > +			if (bridge_connector->bridge_dp)
> > > +				return ERR_PTR(-EBUSY);
> > > +			if (bridge_connector->bridge_hdmi)
> > > +				return ERR_PTR(-EINVAL);
> > > +
> > > +			bridge_connector->bridge_dp = bridge;
> > > +
> > > +		}
> > > +
> > >  		if (!drm_bridge_get_next_bridge(bridge))
> > >  			connector_type = bridge->type;
> > >  
> > > @@ -612,21 +650,21 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
> > >  		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_bridge_connector_hdmi_audio_init(connector, bridge);
> > > +		if (ret)
> > > +			return ERR_PTR(ret);
> > > +	} else if (bridge_connector->bridge_dp) {
> > > +		bridge = bridge_connector->bridge_dp;
> > >  
> > > -			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);
> > > -		}
> > > +		ret = drmm_connector_init(drm, connector,
> > > +					  &drm_bridge_connector_funcs,
> > > +					  connector_type, ddc);
> > > +		if (ret)
> > > +			return ERR_PTR(ret);
> > > +
> > > +		ret = drm_bridge_connector_hdmi_audio_init(connector, bridge);
> > > +		if (ret)
> > > +			return ERR_PTR(ret);
> > >  	} else {
> > >  		ret = drmm_connector_init(drm, connector,
> > >  					  &drm_bridge_connector_funcs,
> > > diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> > > index 496dbbd2ad7edff7f091adfbe62de1e33ef0cf07..40f37444426b1b8ded25da9ba9e2963f18ad6267 100644
> > > --- a/include/drm/drm_bridge.h
> > > +++ b/include/drm/drm_bridge.h
> > > @@ -811,9 +811,21 @@ enum drm_bridge_ops {
> > >  	 *
> > >  	 * 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.
> > > +	 * drivers. Having both HDMI and DisplayPort bridges in the same bridge
> > > +	 * chain is also not allowed.
> > >  	 */
> > >  	DRM_BRIDGE_OP_HDMI = BIT(4),
> > > +	/**
> > > +	 * @DRM_BRIDGE_OP_DisplayPort: The bridge provides DisplayPort connector
> > > +	 * operations. Currently this is limited to the optional HDMI codec
> > > +	 * support.
> > > +	 *
> > > +	 * 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. Having both HDMI and DisplayPort bridges in the same bridge
> > > +	 * chain is also not allowed.
> > > +	 */
> > > +	DRM_BRIDGE_OP_DisplayPort = BIT(5),
> > 
> > The OP bits are not supposed to describe tbe type of bridge, but the
> > operations it implements. I see quite a bit of duplication between HDMI
> > and DisplayPort in this patch. Can we have a single bit named after the
> > feature that you want to support ? The bridge_hdmi and bridge_dp fields
> > should also be merged into a single one.
> 
> In this case these ops actually describe the set of ops implemented by
> the bridge. DRM_BRIDGE_OP_HDMI implements hdmi_tmds_char_rate_valid(),
> hdmi_write_infoframe(), hdmi_clear_infoframe()

Those are required for HDMI bridges (using the common infrastructure).

> and hdmi_audio_*() callbacks.

But those are certainly not required.

If the OP enum is meant to list what a bridge implements, then we need
to have a different enum for video, audio, and CEC.

Maxime