Re: [PATCH 2/8] drm/i915: Stop encryption for repeater with no sink

Sean Paul
2018-02-02T14:13:26Z

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.

>
> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
> ---
> 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