| Message ID | 20220701104859.1236585-1-arun.r.murthy@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [PATCHv2] drm/i915/dp: wait on timeout before retry | expand |
On Fri, 01 Jul 2022, Arun R Murthy <arun.r.murthy@intel.com> wrote: > On linktraining error/timeout before retry need to wait for 400usec as > per the DP CTS spec1.2 > > The patch with commit 74ebf294a1dd ("drm/i915: Add a delay in Displayport > AUX transactions for compliance testing") > removes this delay mentioning the hardware already meets this requirement, > but as per the spec the delay mentioned in the spec specifies how long to > wait for the receiver response before timeout. So the delay here to wait > for timeout and not a delay after timeout. The DP spec specifies a delay > after timeout and hence adding this delay. > > v2: fixed checkpatch errors and warnings > > Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com> > --- > drivers/gpu/drm/i915/display/intel_dp_aux.c | 8 ++------ > 1 file changed, 2 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c > index 2bc119374555..3fcff3995009 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c > @@ -286,13 +286,9 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp, > /* > * 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_TIME_OUT_ERROR) > - continue; > - > - if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) { > + if (status & (DP_AUX_CH_CTL_RECEIVE_ERROR | > + DP_AUX_CH_CTL_TIME_OUT_ERROR)) { > usleep_range(400, 500); > continue; > } Hate to be a nag, but this is what the indentation should look like: - if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) { + if (status & (DP_AUX_CH_CTL_RECEIVE_ERROR | + DP_AUX_CH_CTL_TIME_OUT_ERROR)) { usleep_range(400, 500); continue; } i.e. leading tabs, then spaces. It'll pay off to have the editor do this for you. BR, Jani.
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c index 2bc119374555..3fcff3995009 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c @@ -286,13 +286,9 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp, /* * 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_TIME_OUT_ERROR) - continue; - - if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) { + if (status & (DP_AUX_CH_CTL_RECEIVE_ERROR | + DP_AUX_CH_CTL_TIME_OUT_ERROR)) { usleep_range(400, 500); continue; }
On linktraining error/timeout before retry need to wait for 400usec as per the DP CTS spec1.2 The patch with commit 74ebf294a1dd ("drm/i915: Add a delay in Displayport AUX transactions for compliance testing") removes this delay mentioning the hardware already meets this requirement, but as per the spec the delay mentioned in the spec specifies how long to wait for the receiver response before timeout. So the delay here to wait for timeout and not a delay after timeout. The DP spec specifies a delay after timeout and hence adding this delay. v2: fixed checkpatch errors and warnings Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com> --- drivers/gpu/drm/i915/display/intel_dp_aux.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)