> On Thu, 12 Sep 2024, Arun R Murthy <arun.r.murthy@xxxxxxxxx> wrote:
> > DP Source should be reading AUX_RD interval after we get adjusted
> > TX_FFE_PRESET_VALUE from the DP Sink. (before actually adjusting in DP
> > Source)
>
> I don't think that's correct. See below.
>
Will correct the statement.
> > Signed-off-by: Srikanth V NagaVenkata
> > <nagavenkata.srikanth.v@xxxxxxxxx>
> > Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx>
> > ---
> > .../gpu/drm/i915/display/intel_dp_link_training.c | 12 ++++++------
> > 1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > index f41b69840ad9..ca179bed46ad 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > @@ -1419,12 +1419,6 @@ intel_dp_128b132b_lane_eq(struct intel_dp
> *intel_dp,
> > for (try = 0; try < max_tries; try++) {
> > fsleep(delay_us);
> >
> > - /*
> > - * The delay may get updated. The transmitter shall read the
> > - * delay before link status during link training.
> > - */
> > - delay_us =
> drm_dp_128b132b_read_aux_rd_interval(&intel_dp->aux);
> > -
> > if (drm_dp_dpcd_read_link_status(&intel_dp->aux, link_status)
> < 0) {
> > lt_err(intel_dp, DP_PHY_DPRX, "Failed to read link
> status\n");
> > return false;
> > @@ -1457,6 +1451,12 @@ intel_dp_128b132b_lane_eq(struct intel_dp
> *intel_dp,
> > lt_err(intel_dp, DP_PHY_DPRX, "Failed to update TX
> FFE settings\n");
> > return false;
> > }
> > +
> > + /*
> > + * The delay may get updated. The transmitter shall read the
> > + * delay before link status during link training.
> > + */
> > + delay_us =
> drm_dp_128b132b_read_aux_rd_interval(&intel_dp->aux);
>
> This is clearly an improvement, but Figure 3-52 of DP 2.1a has "Read
> AUX_RD_INTERVAL value" before "Adjust requested the TX_FFE_PRESET_VALUE
> by a DPRX/LTTPR_UFP setting". Yes, in the same box in the flow chart, but
> before.
>
> Sticking with the spec, the read should be placed above this comment:
>
> /* Update signal levels and training set as requested. */
>
> Be sure to reference the spec in the commit message.
>
Yes, agree Will update this in the next version.
Thanks and Regards,
Arun R Murthy
--------------------
