On Thu, Jul 23, 2015 at 04:35:50PM -0700, Rodrigo Vivi wrote:
> 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>
Looks good.
> ---
> 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");
Isn't this line a little too long?
> + } 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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