Re: [PATCH v3 07/16] drm/i915/hdcp: Enable Gen12 HDCP 1.4 DP MST support

[Anshuman Gupta <anshuman.gupta@intel.com>]

On 2020-10-27 at 11:59:14 +0530, Shankar, Uma wrote:
> 
> 
> > -----Original Message-----
> > From: Anshuman Gupta <anshuman.gupta@intel.com>
> > Sent: Friday, October 23, 2020 5:51 PM
> > To: intel-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org
> > Cc: seanpaul@chromium.org; Nikula, Jani <jani.nikula@intel.com>; C,
> > Ramalingam <ramalingam.c@intel.com>; Li, Juston <juston.li@intel.com>;
> > Shankar, Uma <uma.shankar@intel.com>; Gupta, Anshuman
> > <anshuman.gupta@intel.com>
> > Subject: [PATCH v3 07/16] drm/i915/hdcp: Enable Gen12 HDCP 1.4 DP MST
> > support
> > 
> > Enable HDCP 1.4 over DP MST for Gen12.
> > This also enable the stream encryption support for older generations, which was
> > missing earlier.
> > 
> > v2:
> > - Added debug print for stream encryption.
> > - Disable the hdcp on port after disabling last stream
> >   encryption.
> 
> Don't see port disable here, Am I missing something.
> 
> > 
> > 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   | 46 ++++++++++++++-------
> >  2 files changed, 35 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 61252d4be3dd..46c9bd588db1 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);
> > @@ -790,19 +801,26 @@ 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);
> > +	/*
> > +	 * Step 1: Deselect HDCP Multiplestream Bit.
> > +	 * Step 2: poll for stream encryption status to be disable.
> > +	 */
> 
> The above comment should be inside the callback, doesn't add value here.
stream_encryption call back is common for enable/disable stream encryption.
probbaly it would be better to nuke the above comment in case not adds value here.
Thanks,
Anshuman.
> 
> > +	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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