[PATCH v6 04/18] drm/i915/hdcp: No HDCP when encoder is't initialized

[Anshuman Gupta]

On 2020-12-04 at 14:32:16 +0530, Ramalingam C wrote:
> On 2020-11-26 at 13:07:08 +0530, Anshuman Gupta wrote:
> > There can be situation when DP MST connector is created without
> > mst modeset being done, in those cases connector->encoder will be
> > NULL. MST connector->encoder initializes after modeset.
> 
> This patch is to reject the HDCP request on MST connector without
> encoder initialized(modeset). But userspace are not supposed to request hdcp at such
> scenario right?.
AFAIU user space doesn't know about DP MST topology until unless it parse
PATH property. This crash oberved on chrome OS with DP MST dock.
>From driver POV it should avoid kernel crash in such cases.

Thanks,
Anshuman Gupta. 
> 
> Ram
> 
> > Don't enable HDCP in such cases to prevent any crash.
> > 
> > Cc: Ramalingam C <ramalingam.c at intel.com>
> > Cc: Juston Li <juston.li at intel.com>
> > Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_hdcp.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
> > index b9d8825e2bb1..7d63e9495956 100644
> > --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> > @@ -2106,6 +2106,12 @@ int intel_hdcp_enable(struct intel_connector *connector,
> >  	if (!hdcp->shim)
> >  		return -ENOENT;
> >  
> > +	if (!connector->encoder) {
> > +		drm_err(&dev_priv->drm, "[%s:%d] encoder is not initialized\n",
> > +			connector->base.name, connector->base.base.id);
> > +		return -ENODEV;
> > +	}
> > +
> >  	mutex_lock(&hdcp->mutex);
> >  	mutex_lock(&dig_port->hdcp_mutex);
> >  	drm_WARN_ON(&dev_priv->drm,
> > -- 
> > 2.26.2
> >