On Tue, May 12, 2020 at 08:41:44PM +0300, Ville Syrjala wrote: > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > The DP spec says: > "The transmitter shall support at least three levels of voltage > swing (Levels 0, 1, and 2). > > If only three levels of voltage swing are supported (VOLTAGE > SWING SET field (bits 1:0) are programmed to 10 (Level 2)), > this bit shall be set to 1, and cleared in all other cases. > > If all four levels of voltage swing are supported (VOLTAGE > SWING SET field (bits 1:0) are programmed to 11 (Level 3)), > this bit shall be set to 1,and cleared in all other cases." > > Let's follow that exactly instead of the current apporach > where we can set those also for vswing/preemph levels 0 or 1 > (or 2 when the platform max is 3). > > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Yep, so the sink could've incorrectly stopped asking for higher vswing levels after it asked for 0 vs+2 pe, when the max vs is 2 for instance. Matches the spec: Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx> > --- > drivers/gpu/drm/i915/display/intel_dp_link_training.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 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 573f93779449..aa7af531bcb8 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c > +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c > @@ -72,8 +72,9 @@ void intel_dp_get_adjust_train(struct intel_dp *intel_dp, > if (p >= preemph_max) > p = preemph_max | DP_TRAIN_MAX_PRE_EMPHASIS_REACHED; > > - voltage_max = min(intel_dp->voltage_max(intel_dp), > - dp_voltage_max(p)); > + v = min(v, dp_voltage_max(p)); > + > + voltage_max = intel_dp->voltage_max(intel_dp); > if (v >= voltage_max) > v = voltage_max | DP_TRAIN_MAX_SWING_REACHED; > > -- > 2.26.2 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
