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drm/i915: Retry HDCP bksv read 

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]

v5:
  Correcting the return value [Seanpaul].

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1517851922-30547-1-git-send-email-ramalingam.c@intel.com
This commit is contained in:
Ramalingam C 2018-02-05 23:02:02 +05:30 committed by Sean Paul
parent cb340bf371
commit f622a71d39
1 changed files with 13 additions and 5 deletions
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18
drivers/gpu/drm/i915/intel_hdcp.c
View File

@ -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)
return ret;
else if (!intel_hdcp_is_ksv_valid(bksv.shim))
/* 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 -ENODEV;
}
I915_WRITE(PORT_HDCP_BKSVLO(port), bksv.reg[0]);
I915_WRITE(PORT_HDCP_BKSVHI(port), bksv.reg[1]);