On Mon, Feb 05, 2018 at 10:44:41PM +0530, Ramalingam C wrote:
> HDCP specification says that when bksv is identified as invalid
> (not with 20 1s), bksv should be re-read and verified.
>
> This patch adds the above mentioned re-read for bksv.
>
> v2:
> Rephrased the commit msg [Seanpaul]
>
> v3:
> do-while to for-loop [Seanpaul]
>
> v4:
> retry only if bksv is invalid and no error msg on each attempt
> [Seanpaul]
>
> Signed-off-by: Ramalingam C <ramalingam.c@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_hdcp.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_hdcp.c b/drivers/gpu/drm/i915/intel_hdcp.c
> index cfd13ee8c534..df0dabab97e1 100644
> --- a/drivers/gpu/drm/i915/intel_hdcp.c
> +++ b/drivers/gpu/drm/i915/intel_hdcp.c
> @@ -397,7 +397,7 @@ static int intel_hdcp_auth(struct intel_digital_port *intel_dig_port,
> struct drm_i915_private *dev_priv;
> enum port port;
> unsigned long r0_prime_gen_start;
> - int ret, i;
> + int ret, i, tries = 2;
> union {
> u32 reg[2];
> u8 shim[DRM_HDCP_AN_LEN];
> @@ -438,11 +438,19 @@ static int intel_hdcp_auth(struct intel_digital_port *intel_dig_port,
> r0_prime_gen_start = jiffies;
>
> memset(&bksv, 0, sizeof(bksv));
> - ret = shim->read_bksv(intel_dig_port, bksv.shim);
> - if (ret)
> +
> + /* HDCP spec states that we must retry the bksv if it is invalid */
> + for (i = 0; i < tries; i++) {
> + ret = shim->read_bksv(intel_dig_port, bksv.shim);
> + if (ret)
> + return ret;
> + if (intel_hdcp_is_ksv_valid(bksv.shim))
> + break;
> + }
> + if (i == tries) {
> + DRM_ERROR("HDCP failed, Bksv is invalid\n");
> return ret;
This will return 0.
> - else if (!intel_hdcp_is_ksv_valid(bksv.shim))
> - return -ENODEV;
> + }
>
> I915_WRITE(PORT_HDCP_BKSVLO(port), bksv.reg[0]);
> I915_WRITE(PORT_HDCP_BKSVHI(port), bksv.reg[1]);
> --
> 2.7.4
>
--
Sean Paul, Software Engineer, Google / Chromium OS
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