Re: [Intel-gfx] [PATCH v5 07/17] drm/i915/hdcp: Enable HDCP 1.4 stream encryption

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

On 2020-11-24 at 19:44:59 +0530, Ramalingam C wrote:
> On 2020-11-11 at 11:50:41 +0530, Anshuman Gupta wrote:
> > Enable HDCP 1.4 DP MST stream encryption.
> > 
> > Enable stream encryption once encryption is enabled on
> > the DP transport driving the link for each stream which
> > has requested encryption.
> > 
> > Disable stream encryption for each stream that no longer
> > requires encryption before disabling HDCP encryption on
> > the link.
> > 
> > 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]
> > v4:
> > - Split the Gen12 HDCP enablement patch. [Ram]
> > - Add connector details in drm_err.
> > 
> > Cc: Ramalingam C <ramalingam.c@intel.com>
> > Reviewed-by: Uma Shankar <uma.shankar@intel.com>
> > Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_hdcp.c | 45 ++++++++++++++++-------
> >  1 file changed, 31 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
> > index 0322a83c151d..e12bd0ac9fb5 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.
> > +1*/
> IMO this function is generic for SST and MST. Why do we document only
> for MST at the top of the function? We can remove them.
Sure i will remove it.
> >  static int intel_hdcp_auth(struct intel_connector *connector)
> >  {
> >  	struct intel_digital_port *dig_port = intel_attached_dig_port(connector);
> > @@ -766,10 +771,17 @@ 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(connector, true);
> > +		if (ret) {
> > +			drm_err(&dev_priv->drm, "[CONNECTOR:%d:%s] Failed to enable HDCP 1.4 stream enc\n",
> All the existing error messgae has the %s:%d, why are we changing it
> here? Could we retain the uniformity?
Sure i will fix this in entire series.
> > +				connector->base.base.id, connector->base.name);
> > +			return ret;
> > +		}
> > +		drm_dbg_kms(&dev_priv->drm, "HDCP 1.4 transcoder: %s stream encrypted\n",
> > +			    transcoder_name(hdcp->stream_transcoder));
> > +	}
> >  
> >  	if (repeater_present)
> >  		return intel_hdcp_auth_downstream(connector);
> > @@ -791,18 +803,23 @@ 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(connector, false);
> > +		if (ret) {
> > +			drm_err(&dev_priv->drm, "[CONNECTOR:%d:%s] Failed to disable HDCP 1.4 stream enc\n",
> same here. remove CONNECTOR ?
> > +				connector->base.base.id, connector->base.name);
> > +			return ret;
> > +		}
> > +		drm_dbg_kms(&dev_priv->drm, "HDCP 1.4 transcoder: %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.
> What is this steps 1-2 here!? Here you are not disabling if other
> streams are encrpted. May be you want to put something like "Untill all
> steams of MST stopped encrypting, dont disable the port encryption"
Sure i will fix this.
Thanks,
Anshuman.
> 
> -Ram
> >  	 */
> > -	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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