On 25-01-03 20:09:42, Dmitry Baryshkov wrote:
> On Fri, Jan 03, 2025 at 02:58:17PM +0200, Abel Vesa wrote:
> > LTTPRs operating modes are defined by the DisplayPort standard and the
> > generic framework now provides a helper to switch between them, which
> > is handling the explicit disabling of non-transparent mode and its
> > disable->enable sequence mentioned in the DP Standard v2.0 section
> > 3.6.6.1.
> >
> > So use the new drm generic helper instead as it makes the code a bit
> > cleaner.
> >
> > Acked-by: Imre Deak <imre.deak@xxxxxxxxx>
> > Signed-off-by: Abel Vesa <abel.vesa@xxxxxxxxxx>
> > ---
> > .../gpu/drm/i915/display/intel_dp_link_training.c | 24 +++++-----------------
> > 1 file changed, 5 insertions(+), 19 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 8b1977cfec503c70f07af716ee2c00e7605c6adf..c5bad311edf7b9a5cebb633b9e9692bae397f9ed 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > @@ -119,9 +119,6 @@ intel_dp_set_lttpr_transparent_mode(struct intel_dp *intel_dp, bool enable)
> > u8 val = enable ? DP_PHY_REPEATER_MODE_TRANSPARENT :
> > DP_PHY_REPEATER_MODE_NON_TRANSPARENT;
> >
> > - if (drm_dp_dpcd_write(&intel_dp->aux, DP_PHY_REPEATER_MODE, &val, 1) != 1)
> > - return false;
> > -
> > intel_dp->lttpr_common_caps[DP_PHY_REPEATER_MODE -
> > DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV] = val;
> >
> > @@ -146,6 +143,7 @@ static bool intel_dp_lttpr_transparent_mode_enabled(struct intel_dp *intel_dp)
> > static int intel_dp_init_lttpr_phys(struct intel_dp *intel_dp, const u8 dpcd[DP_RECEIVER_CAP_SIZE])
> > {
> > int lttpr_count;
> > + int ret;
> >
> > if (!intel_dp_read_lttpr_common_caps(intel_dp, dpcd))
> > return 0;
> > @@ -172,22 +170,8 @@ static int intel_dp_init_lttpr_phys(struct intel_dp *intel_dp, const u8 dpcd[DP_
> > return lttpr_count;
> > }
> >
> > - /*
> > - * See DP Standard v2.0 3.6.6.1. about the explicit disabling of
> > - * non-transparent mode and the disable->enable non-transparent mode
> > - * sequence.
> > - */
> > - intel_dp_set_lttpr_transparent_mode(intel_dp, true);
> > -
> > - /*
> > - * In case of unsupported number of LTTPRs or failing to switch to
> > - * non-transparent mode fall-back to transparent link training mode,
> > - * still taking into account any LTTPR common lane- rate/count limits.
> > - */
> > - if (lttpr_count < 0)
> > - goto out_reset_lttpr_count;
> > -
> > - if (!intel_dp_set_lttpr_transparent_mode(intel_dp, false)) {
> > + ret = drm_dp_lttpr_init(&intel_dp->aux, lttpr_count);
> > + if (ret) {
> > lt_dbg(intel_dp, DP_PHY_DPRX,
> > "Switching to LTTPR non-transparent LT mode failed, fall-back to transparent mode\n");
> >
> > @@ -196,6 +180,8 @@ static int intel_dp_init_lttpr_phys(struct intel_dp *intel_dp, const u8 dpcd[DP_
> > goto out_reset_lttpr_count;
> > }
> >
> > + intel_dp_set_lttpr_transparent_mode(intel_dp, false);
> > +
>
> I think the code now misses a way to update intel_dp->lttpr_common_caps
> in a transparent-mode case:
> intel_dp_set_lttpr_transparent_mode(intel_dp, true).
It is being called if the drm_dp_lttpr_init() returns a non-zero value,
but that is not part of the diff here.
>
> > return lttpr_count;
> >
> > out_reset_lttpr_count:
> >
> > --
> > 2.34.1
> >
>
> --
> With best wishes
> Dmitry
