By Vesa DP 1.2 spec TEST_CRC_COUNT is a "4 bit wrap counter which
increments each time the TEST_CRC_x_x are updated."
However if we are trying to verify the screen hasn't changed we get
same (count, crc) pair twice. Without this patch we would return
-ETIMEOUT in this case.
So, if in 6 vblanks the pair (count, crc) hasn't changed we
return it anyway instead of returning error and let test case decide
if it was right or not.
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dp.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index c7372a1..e99ec7a 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4028,6 +4028,7 @@ 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)
@@ -4042,6 +4043,7 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
goto stop;
}
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.
@@ -4053,17 +4055,24 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
ret = -EIO;
goto stop;
}
- } while (--attempts && (count == 0 || (count == intel_dp->sink_crc.last_count &&
- !memcmp(intel_dp->sink_crc.last_crc, crc,
- 6 * sizeof(u8)))));
+
+ 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));
if (attempts == 0) {
- DRM_DEBUG_KMS("Panel is unable to calculate CRC after 6 vblanks\n");
- ret = -ETIMEDOUT;
- goto stop;
+ 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;
+ }
}
stop:
--
2.1.0
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