[PATCH 4/8] drm/i915: Retry HDCP BKSV read

[Ramalingam C <ramalingam.c@intel.com>]

When BKSV is invalid, to mitigate any communication errors,
BKSV is read once again.

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
---
 drivers/gpu/drm/i915/intel_hdcp.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_hdcp.c b/drivers/gpu/drm/i915/intel_hdcp.c
index b3f407cef8b0..fa2e7c727d00 100644
--- a/drivers/gpu/drm/i915/intel_hdcp.c
+++ b/drivers/gpu/drm/i915/intel_hdcp.c
@@ -401,7 +401,7 @@ static int intel_hdcp_auth(struct intel_connector *connector)
 	struct drm_i915_private *dev_priv;
 	enum port port;
 	unsigned long r0_prime_gen_start;
-	int ret, i;
+	int ret, i, retry = 1;
 	union {
 		u32 reg[2];
 		u8 shim[DRM_HDCP_AN_LEN];
@@ -443,11 +443,16 @@ static int intel_hdcp_auth(struct intel_connector *connector)
 	r0_prime_gen_start = jiffies;
 
 	memset(&bksv, 0, sizeof(bksv));
-	ret = shim->read_bksv(intel_dig_port, bksv.shim);
+
+	do {
+		ret = shim->read_bksv(intel_dig_port, bksv.shim);
+		if (!ret)
+			if (!intel_hdcp_is_ksv_valid(bksv.shim))
+				ret = -ENODEV;
+	} while (ret && retry--);
+
 	if (ret)
 		return ret;
-	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

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