From aabc95dcf200908993573b2019ff5210121bcba9 Mon Sep 17 00:00:00 2001 From: Rodrigo Vivi Date: Thu, 23 Jul 2015 16:35:50 -0700 Subject: [PATCH] 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 Reviewed-by: Rafael Antognolli Signed-off-by: Daniel Vetter --- 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 abcc2a36aa95..54e9b5380aa7 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -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: -- 2.20.1