[Intel-gfx] [PATCH] drm/i915/debugfs: HDCP capability enc NULL check

[Gupta, Anshuman]

> -----Original Message-----
> From: Imre Deak <imre.deak at intel.com>
> Sent: Thursday, February 4, 2021 11:58 PM
> To: Gupta, Anshuman <anshuman.gupta at intel.com>
> Cc: intel-gfx at lists.freedesktop.org
> Subject: Re: [Intel-gfx] [PATCH] drm/i915/debugfs: HDCP capability enc NULL
> check
> 
> On Fri, Jan 29, 2021 at 01:30:43PM +0530, Anshuman Gupta wrote:
> > DP-MST connector encoder initializes at modeset Adding a
> > connector->encoder NULL check in order to avoid any NULL pointer
> > dereference.
> > intel_hdcp_enable() already handle this but debugfs can also invoke
> > the intel_{hdcp,hdcp2_capable}.
> > Handling it gracefully.
> >
> > Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_hdcp.c | 14 ++++++++++++--
> >  1 file changed, 12 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c
> > b/drivers/gpu/drm/i915/display/intel_hdcp.c
> > index ae1371c36a32..58af323d189a 100644
> > --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> > @@ -135,11 +135,16 @@ int intel_hdcp_read_valid_bksv(struct
> > intel_digital_port *dig_port,
> >  /* Is HDCP1.4 capable on Platform and Sink */  bool
> > intel_hdcp_capable(struct intel_connector *connector)  {
> > -	struct intel_digital_port *dig_port =
> intel_attached_dig_port(connector);
> > +	struct intel_digital_port *dig_port;
> >  	const struct intel_hdcp_shim *shim = connector->hdcp.shim;
> >  	bool capable = false;
> >  	u8 bksv[5];
> >
> > +	if (!connector->encoder)
> > +		return -ENODEV;
> 
> I assume this is needed when called from i915_hdcp_sink_capability debugfs
> entry. That one is lacking the locking for the connector, but is that entry really
> needed? We print the same info already from the i915_display_info entry which
> has the proper locking and encoder check.
Historically HDCP capability added to i915_display_info later to debug CI machine as i915_display_info available as CI logs.
Now the plans i915_display_info  should only show the monitor capability.
and i915_hdcp_sink_capability will check both sink and platform capability.

Thanks,
Anshuman Gupta.
> 
> > +
> > +	dig_port = intel_attached_dig_port(connector);
> > +
> >  	if (!shim)
> >  		return capable;
> >
> > @@ -156,11 +161,16 @@ bool intel_hdcp_capable(struct intel_connector
> > *connector)
> >  /* Is HDCP2.2 capable on Platform and Sink */  bool
> > intel_hdcp2_capable(struct intel_connector *connector)  {
> > -	struct intel_digital_port *dig_port =
> intel_attached_dig_port(connector);
> > +	struct intel_digital_port *dig_port;
> >  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> >  	struct intel_hdcp *hdcp = &connector->hdcp;
> >  	bool capable = false;
> >
> > +	if (!connector->encoder)
> > +		return -ENODEV;
> > +
> > +	dig_port = intel_attached_dig_port(connector);
> > +
> >  	/* I915 support for HDCP2.2 */
> >  	if (!hdcp->hdcp2_supported)
> >  		return false;
> > --
> > 2.26.2
> >
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