Re: [PATCH v4 07/16] drm/i915/hdcp: Enable Gen12 HDCP 1.4 DP MST support

[Ramalingam C <ramalingam.c@intel.com>]

On 2020-10-27 at 22:11:59 +0530, Anshuman Gupta wrote:
> Enable HDCP 1.4 over DP MST for Gen12.
> This also enable the stream encryption support for
> older generations, which was missing earlier.
It will be nice to have them in separate patches.

-Ram
> 
> v2:
> - Added debug print for stream encryption.
> - Disable the hdcp on port after disabling last stream
>   encryption.
> v3:
> - Cosmetic change, removed the value less comment. [Uma]
> 
> Cc: Ramalingam C <ramalingam.c@intel.com>
> Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp_mst.c | 10 ++---
>  drivers/gpu/drm/i915/display/intel_hdcp.c   | 43 ++++++++++++++-------
>  2 files changed, 32 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index 16865b200062..f00e12fc83e8 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -826,13 +826,9 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
>  	intel_attach_force_audio_property(connector);
>  	intel_attach_broadcast_rgb_property(connector);
>  
> -
> -	/* TODO: Figure out how to make HDCP work on GEN12+ */
> -	if (INTEL_GEN(dev_priv) < 12) {
> -		ret = intel_dp_init_hdcp(dig_port, intel_connector);
> -		if (ret)
> -			DRM_DEBUG_KMS("HDCP init failed, skipping.\n");
> -	}
> +	ret = intel_dp_init_hdcp(dig_port, intel_connector);
> +	if (ret)
> +		drm_dbg_kms(&dev_priv->drm, "HDCP init failed, skipping.\n");
>  
>  	/*
>  	 * Reuse the prop from the SST connector because we're
> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
> index 0322a83c151d..937af4aeaac2 100644
> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> @@ -612,7 +612,12 @@ int intel_hdcp_auth_downstream(struct intel_connector *connector)
>  	return ret;
>  }
>  
> -/* Implements Part 1 of the HDCP authorization procedure */
> +/*
> + * Implements Part 1 of the HDCP authorization procedure.
> + * Authentication Part 1 steps for Multi-stream DisplayPort.
> + * Step 1. Auth Part 1 sequence on the driving MST Trasport Link.
> + * Step 2. Enable encryption for each stream that requires encryption.
> + */
>  static int intel_hdcp_auth(struct intel_connector *connector)
>  {
>  	struct intel_digital_port *dig_port = intel_attached_dig_port(connector);
> @@ -766,10 +771,16 @@ static int intel_hdcp_auth(struct intel_connector *connector)
>  		return -ETIMEDOUT;
>  	}
>  
> -	/*
> -	 * XXX: If we have MST-connected devices, we need to enable encryption
> -	 * on those as well.
> -	 */
> +	/* DP MST Auth Part 1 Step 2.a and Step 2.b */
> +	if (shim->stream_encryption) {
> +		ret = shim->stream_encryption(dig_port, true);
> +		if (ret) {
> +			drm_err(&dev_priv->drm, "Failed to enable HDCP 1.4 stream enc\n");
> +			return ret;
> +		}
> +		drm_dbg_kms(&dev_priv->drm, "HDCP 1.4 tras %s stream encrypted\n",
> +			    transcoder_name(hdcp->stream_transcoder));
> +	}
>  
>  	if (repeater_present)
>  		return intel_hdcp_auth_downstream(connector);
> @@ -791,18 +802,22 @@ static int _intel_hdcp_disable(struct intel_connector *connector)
>  	drm_dbg_kms(&dev_priv->drm, "[%s:%d] HDCP is being disabled...\n",
>  		    connector->base.name, connector->base.base.id);
>  
> +	if (hdcp->shim->stream_encryption) {
> +		ret = hdcp->shim->stream_encryption(dig_port, false);
> +		if (ret) {
> +			drm_err(&dev_priv->drm, "Failed to disable HDCP 1.4 stream enc\n");
> +			return ret;
> +		}
> +		drm_dbg_kms(&dev_priv->drm, "HDCP 1.4 trans %s stream encryption disabled\n",
> +			    transcoder_name(hdcp->stream_transcoder));
> +	}
> +
>  	/*
> -	 * If there are other connectors on this port using HDCP, don't disable
> -	 * it. Instead, toggle the HDCP signalling off on that particular
> -	 * connector/pipe and exit.
> +	 * If there are other connectors on this port using HDCP, don't disable it.
> +	 * Repeat steps 1-2 for each stream that no longer requires encryption.
>  	 */
> -	if (dig_port->num_hdcp_streams > 0) {
> -		ret = hdcp->shim->toggle_signalling(dig_port,
> -						    cpu_transcoder, false);
> -		if (ret)
> -			DRM_ERROR("Failed to disable HDCP signalling\n");
> +	if (dig_port->num_hdcp_streams > 0)
>  		return ret;
> -	}
>  
>  	hdcp->hdcp_encrypted = false;
>  	intel_de_write(dev_priv, HDCP_CONF(dev_priv, cpu_transcoder, port), 0);
> -- 
> 2.26.2
> 
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