On Fri, Feb 02, 2018 at 08:33:38PM +0530, Ramalingam C wrote: > > > On Friday 02 February 2018 08:18 PM, Sean Paul wrote: > > On Fri, Feb 02, 2018 at 07:42:47PM +0530, Ramalingam C wrote: > > > > > > On Friday 02 February 2018 07:43 PM, Sean Paul wrote: > > > > On Fri, Feb 02, 2018 at 04:15:14PM +0530, Ramalingam C wrote: > > > > > If a HDCP repeater is detected with zero hdcp authenticated > > > > > downstream devices, there are two option as below: > > > > > > > > > > 1. Dont continue on second stage authentication. Disable encryption. > > > > > 2. Continue with second stage authentication excluding the KSV list and > > > > > continue encryption on success. > > > > > > > > > > This patch adopts the option 1. > > > > It doesn't seem that hard to adopt option 2 and avoid failure. That would result > > > > in a better experience. > > > True. Not too much effort for option 2. But I am not seeing any ROI out of > > > it at this point. > > > what is the benefit of encrypting if repeater cant use it, as it has 0 sinks > > > attached to it. > > > Still do we want option two? > > Is it possible the repeater itself has video output? I'm also worried about > > non-compliant displays which may report having a repeater. If these aren't > > possible, I agree. Just beef up the comment like "If there are no downstream > > devices, spec requires we disable all encryption. So fail here to ensure hdcp is > > disabled" > > > > Sean > > When spec provide an option that we can disable the HDCP encryption incase > of repeater with device count 0, that means repeaters cant have display. > > Display which claims to be a repeater, mostly wont pass the second stage > authentication meant for repeaters. So we need not worry about them. > > Sure as you mentioned i will rephrase the commit message with these informations. Not just the commit message. Please also update the comment in the code so it's clear. Sean > > --Ram > > > > > > -Ram > > > > > Signed-off-by: Ramalingam C <ramalingam.c@xxxxxxxxx> > > > > > --- > > > > > drivers/gpu/drm/i915/intel_hdcp.c | 4 ++-- > > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > > > > > diff --git a/drivers/gpu/drm/i915/intel_hdcp.c b/drivers/gpu/drm/i915/intel_hdcp.c > > > > > index 0021511ae4d7..182a3c8a4e4a 100644 > > > > > --- a/drivers/gpu/drm/i915/intel_hdcp.c > > > > > +++ b/drivers/gpu/drm/i915/intel_hdcp.c > > > > > @@ -175,10 +175,10 @@ int intel_hdcp_auth_downstream(struct intel_connector *connector) > > > > > return -EPERM; > > > > > } > > > > > - /* If there are no downstream devices, we're all done. */ > > > > > + /* If there are no downstream devices, we're not encrypting. */ > > > > > num_downstream = DRM_HDCP_NUM_DOWNSTREAM(bstatus[0]); > > > > > if (num_downstream == 0) > > > > > - return 0; > > > > > + return -EINVAL; > > > > > ksv_fifo = kzalloc(num_downstream * DRM_HDCP_KSV_LEN, GFP_KERNEL); > > > > > if (!ksv_fifo) > > > > > -- > > > > > 2.7.4 > > > > > > -- Sean Paul, Software Engineer, Google / Chromium OS _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
