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drm/i915: Dont -ETIMEDOUT on identical new and previous (count, crc). 

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@intel.com>
Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Rodrigo Vivi 2015-07-23 16:35:50 -07:00 committed by Daniel Vetter
parent 621d4c76fd
commit aabc95dcf2
1 changed files with 15 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
drivers/gpu/drm/i915/intel_dp.c
View File

@ -4065,6 +4065,7 @@ 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)
@ -4079,6 +4080,7 @@ 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.
@ -4090,17 +4092,24 @@ 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: