> On Mon, 27 Jun 2022, Arun R Murthy <arun.r.murthy@xxxxxxxxx> wrote: > > On linktraining error/timeout before retry need to wait for 400usec as > > per the DP CTS spec1.2 The patch with commit id > > 74ebf294a1dd816bdc248ac733009a8915d59eb5 > > drm/i915: Add a delay in Displayport AUX transactions for compliance > > testing > > Please reference other commits like this: commit 74ebf294a1dd > ("drm/i915: Add a delay in Displayport AUX transactions for compliance > testing") > > I've got this git alias in my .gitconfig: > > cite = "!f() { git log -1 '--pretty=format:%H (\"%s\")%n' $1 | sed -e > 's/\\([0-f]\\{12\\}\\)[0-f]*/\\1/'; }; f" > > And you can use 'git cite <commit-ish>' to give you the right format. > Will correct this! > > 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. > > Please try to reflow commit messages to about 72 characters. > Commit msg is maintained to be 72 char, but the patch details added might be misleading. Will correct them! > I had a bit of a hard time parsing the above, but basically you're saying that > the hardware handles and flags the timeout, but the DP spec says we need to > wait 400 us *after* the error condition. Makes sense, though I didn't have > the time to read the specs to verify. > > > > > Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx> > > --- > > 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..a1fef1645d6a 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)) { > > Please check the indentation here. The DP_AUX_CH_* should start in the > same column. > Done! Thanks and Regards, Arun R Murthy --------------------