| Message ID | 1428682372-21586-6-git-send-email-tprevite@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
2015-04-10 13:12 GMT-03:00 Todd Previte <tprevite@gmail.com>: > The Displayport Link Layer Compliance Testing Specification 1.2 rev 1.1 > specifies that repeated AUX transactions after a failure (no response / > invalid response) must have a minimum delay of 400us before the resend can > occur. Tests 4.2.1.1 and 4.2.1.2 are two tests that require this specifically. > > Also, the check for DP_AUX_CH_CTL_TIME_OUT_ERROR has been moved out into a > separate case. This case just continues with the next iteration of the loop > as the HW has already waited the required amount of time. > > V2: > - Changed udelay() to usleep_range() > V3: > - Removed extraneous check for timeout > - Updated comment to reflect this change > V4: > - Reformatted a comment > V5: > - Added separate check for HW timeout on AUX transactions. A message > is logged upon detection of this case. > V6: > - Add continue statement to HW timeout detect case > - Remove the log message indicating a timeout has been > detected (review feedback) > V7: > - Updated the commit message to remove verbage about the HW timeout > case that is no longer valid. > > Signed-off-by: Todd Previte <tprevite@gmail.com> Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com> > --- > drivers/gpu/drm/i915/intel_dp.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c > index a5dfaff..77b6b15 100644 > --- a/drivers/gpu/drm/i915/intel_dp.c > +++ b/drivers/gpu/drm/i915/intel_dp.c > @@ -877,9 +877,18 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, > DP_AUX_CH_CTL_TIME_OUT_ERROR | > DP_AUX_CH_CTL_RECEIVE_ERROR); > > - if (status & (DP_AUX_CH_CTL_TIME_OUT_ERROR | > - DP_AUX_CH_CTL_RECEIVE_ERROR)) > + if (status & DP_AUX_CH_CTL_TIME_OUT_ERROR) > continue; > + > + /* DP CTS 1.2 Core Rev 1.1, 4.2.1.1 & 4.2.1.2 > + * 400us delay required for errors and timeouts > + * Timeout errors from the HW already meet this > + * requirement so skip to next iteration > + */ > + if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) { > + usleep_range(400, 500); > + continue; > + } > if (status & DP_AUX_CH_CTL_DONE) > break; > } > -- > 1.9.1 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index a5dfaff..77b6b15 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -877,9 +877,18 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, DP_AUX_CH_CTL_TIME_OUT_ERROR | DP_AUX_CH_CTL_RECEIVE_ERROR); - if (status & (DP_AUX_CH_CTL_TIME_OUT_ERROR | - DP_AUX_CH_CTL_RECEIVE_ERROR)) + if (status & DP_AUX_CH_CTL_TIME_OUT_ERROR) continue; + + /* DP CTS 1.2 Core Rev 1.1, 4.2.1.1 & 4.2.1.2 + * 400us delay required for errors and timeouts + * Timeout errors from the HW already meet this + * requirement so skip to next iteration + */ + if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) { + usleep_range(400, 500); + continue; + } if (status & DP_AUX_CH_CTL_DONE) break; }
The Displayport Link Layer Compliance Testing Specification 1.2 rev 1.1 specifies that repeated AUX transactions after a failure (no response / invalid response) must have a minimum delay of 400us before the resend can occur. Tests 4.2.1.1 and 4.2.1.2 are two tests that require this specifically. Also, the check for DP_AUX_CH_CTL_TIME_OUT_ERROR has been moved out into a separate case. This case just continues with the next iteration of the loop as the HW has already waited the required amount of time. V2: - Changed udelay() to usleep_range() V3: - Removed extraneous check for timeout - Updated comment to reflect this change V4: - Reformatted a comment V5: - Added separate check for HW timeout on AUX transactions. A message is logged upon detection of this case. V6: - Add continue statement to HW timeout detect case - Remove the log message indicating a timeout has been detected (review feedback) V7: - Updated the commit message to remove verbage about the HW timeout case that is no longer valid. Signed-off-by: Todd Previte <tprevite@gmail.com> --- drivers/gpu/drm/i915/intel_dp.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)