| Message ID | 1403647974-42377-3-git-send-email-tprevite@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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@gmail.com> > --- > 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;
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)) { + /* 400us delay between transactions for errors/timeouts + required for DP compliance testing */ + udelay(400); continue; + } if (status & DP_AUX_CH_CTL_DONE) break; }
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@gmail.com> --- drivers/gpu/drm/i915/intel_dp.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)