[PATCH v2 1/3] drm/display: bridge-connector: add DisplayPort bridges

[Laurent Pinchart]

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 at 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