drm/i915: Stop tracking last calculated Sink CRC.

It was created at 'commit aabc95dc (drm/i915: Dont -ETIMEDOUT
on identical new and previous (count, crc).")' becase the counter
wasn't reliable.

Now that we properly wait for the counter to be reset we can rely
a bit more in the counter.

Also that patch stopped to return -ETIMEDOUT so the test case is
unable to skip when it is unreliable and end up in many fails
that should be skip instead.

So, with the counter more reliable we can remove
this hack that just makes things more confusing when test cases
are really expecting the same CRC and let test case skip if that's
not the case.
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -4011,8 +4011,6 @@ static int intel_dp_sink_crc_start(struct intel_dp *intel_dp)
 	if (!(buf & DP_TEST_CRC_SUPPORTED))
 		return -ENOTTY;
 
-	intel_dp->sink_crc.last_count = buf & DP_TEST_COUNT_MASK;
-
 	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK, &buf) < 0)
 		return -EIO;
 
@@ -4037,7 +4035,6 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
 	u8 buf;
 	int count, ret;
 	int attempts = 6;
-	bool old_equal_new;
 
 	ret = intel_dp_sink_crc_start(intel_dp);
 	if (ret)
@@ -4053,35 +4050,17 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
 		}
 		count = buf & DP_TEST_COUNT_MASK;
 
-		/*
-		 * Count might be reset during the loop. In this case
-		 * last known count needs to be reset as well.
-		 */
-		if (count == 0)
-			intel_dp->sink_crc.last_count = 0;
-
-		if (drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_CRC_R_CR, crc, 6) < 0) {
-			ret = -EIO;
-			goto stop;
-		}
-
-		old_equal_new = (count == intel_dp->sink_crc.last_count &&
-				 !memcmp(intel_dp->sink_crc.last_crc, crc,
-					 6 * sizeof(u8)));
-
-	} while (--attempts && (count == 0 || old_equal_new));
-
-	intel_dp->sink_crc.last_count = buf & DP_TEST_COUNT_MASK;
-	memcpy(intel_dp->sink_crc.last_crc, crc, 6 * sizeof(u8));
+	} while (--attempts && count == 0);
 
 	if (attempts == 0) {
-		if (old_equal_new) {
-			DRM_DEBUG_KMS("Unreliable Sink CRC counter: Current returned CRC is identical to the previous one\n");
-		} else {
 		DRM_ERROR("Panel is unable to calculate any CRC after 6 vblanks\n");
 		ret = -ETIMEDOUT;
 		goto stop;
 	}
+
+	if (drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_CRC_R_CR, crc, 6) < 0) {
+		ret = -EIO;
+		goto stop;
 	}
 
 stop:

drivers/gpu/drm/i915/intel_drv.h

@@ -740,8 +740,6 @@ enum link_m_n_set {
 
 struct sink_crc {
 	bool started;
-	u8 last_crc[6];
-	int last_count;
 };
 
 struct intel_dp {