[Intel-gfx] [PATCH 2/2] drm/i915/ddi: Don't rewrite DDI_BUF_CTL reg during DP link training

[Imre Deak]

On Tue, Jul 14, 2020 at 07:08:33PM +0300, Ville Syrjälä wrote:
> On Tue, Jul 14, 2020 at 06:31:41PM +0300, Imre Deak wrote:
> > The driver enables the DDI function in the DDI_BUF_CTL register before
> > starting the link training and disables it when disabling the output. It
> > also gets disabled/re-enabled during link re-trainining.
> > 
> > Except of the above the value we program to the register (intel_dp->DP)
> > doesn't change, so no need to reprogram the register when changing the
> > link training patterns.
> > 
> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> 
> The only concern I had was the buf trans stuff for hsw/bdw/skl,
> but looks like hsw_set_signal_levels() does everything we need.

Ok, I missed this part, will fix the commit message.

> 
> Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> > ---
> >  drivers/gpu/drm/i915/display/intel_ddi.c | 4 ----
> >  1 file changed, 4 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> > index c467f18d5e1b..424d59671561 100644
> > --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> > @@ -4060,7 +4060,6 @@ static void intel_ddi_set_link_train(struct intel_dp *intel_dp,
> >  {
> >  	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> >  	u8 train_pat_mask = drm_dp_training_pattern_mask(intel_dp->dpcd);
> > -	enum port port = dp_to_dig_port(intel_dp)->base.port;
> >  	u32 temp;
> >  
> >  	temp = intel_de_read(dev_priv, intel_dp->regs.dp_tp_ctl);
> > @@ -4085,9 +4084,6 @@ static void intel_ddi_set_link_train(struct intel_dp *intel_dp,
> >  	}
> >  
> >  	intel_de_write(dev_priv, intel_dp->regs.dp_tp_ctl, temp);
> > -
> > -	intel_de_write(dev_priv, DDI_BUF_CTL(port), intel_dp->DP);
> > -	intel_de_posting_read(dev_priv, DDI_BUF_CTL(port));
> >  }
> >  
> >  static void intel_ddi_set_idle_link_train(struct intel_dp *intel_dp)
> > -- 
> > 2.23.1
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel