On Tue, Jun 24, 2014 at 03:12:50PM -0700, Todd Previte wrote:
> Several compliance tests require that follow-up AUX transactions (after a
> failure or no response) are not resent sooner than 400us later. Add a 400us
> delay to the response time of any failed transaction to account for this.
>
> Signed-off-by: Todd Previte <tprevite@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_dp.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 3bd1780..43fcabe 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -561,8 +561,12 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
> DP_AUX_CH_CTL_RECEIVE_ERROR);
>
> if (status & (DP_AUX_CH_CTL_TIME_OUT_ERROR |
> - DP_AUX_CH_CTL_RECEIVE_ERROR))
> + DP_AUX_CH_CTL_RECEIVE_ERROR)) {
I think "required for DP compliance testing" is a little verbose and can
be shortened to "DP requires". If you have a spec reference handy, that
would be useful.
/* 10.2.1: DP requires 400us delay after an error. */
> + /* 400us delay between transactions for errors/timeouts
> + required for DP compliance testing */
> + udelay(400);
> continue;
> + }
> if (status & DP_AUX_CH_CTL_DONE)
> break;
--
Chris Wilson, Intel Open Source Technology Centre
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