[PATCH 2/7] drm/i915/vrr: Do not overwrite TRANS_PUSH PSR Frame Change Enable

[Hogander, Jouni]

On Thu, 2024-10-10 at 15:06 +0300, Ville Syrjälä wrote:
> On Thu, Oct 10, 2024 at 08:33:11AM +0300, Jouni Högander wrote:
> > Currently vrr code is overwriting possibly set PSR PR Frame Change
> > Enable
> > bit in TRANS_PUSH register. Avoid this by using rmw instead of
> > write.
> 
> RMWs are not good if we ever want to do this from DSB/etc. We should
> know what the state should be and just program that in.
> 
> Does the PSR bit here have to match the PSR_CTL enable bit or
> could we just always set the bit here based on has_psr whether
> PSR is currently active or not?

I will try that out. I'll guess this should be ok.

BR,

Jouni Högander
> 
> > 
> > Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_vrr.c | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c
> > b/drivers/gpu/drm/i915/display/intel_vrr.c
> > index 9a51f5bac3071..8b4e3f938efea 100644
> > --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> > @@ -339,8 +339,8 @@ void intel_vrr_enable(const struct
> > intel_crtc_state *crtc_state)
> >         if (!crtc_state->vrr.enable)
> >                 return;
> >  
> > -       intel_de_write(display, TRANS_PUSH(display,
> > cpu_transcoder),
> > -                      TRANS_PUSH_EN);
> > +       intel_de_rmw(display, TRANS_PUSH(display, cpu_transcoder),
> > 0,
> > +                    TRANS_PUSH_EN);
> >  
> >         if (HAS_AS_SDP(display))
> >                 intel_de_write(display,
> > @@ -371,7 +371,9 @@ void intel_vrr_disable(const struct
> > intel_crtc_state *old_crtc_state)
> >         intel_de_wait_for_clear(display,
> >                                 TRANS_VRR_STATUS(display,
> > cpu_transcoder),
> >                                 VRR_STATUS_VRR_EN_LIVE, 1000);
> > -       intel_de_write(display, TRANS_PUSH(display,
> > cpu_transcoder), 0);
> > +
> > +       intel_de_rmw(display, TRANS_PUSH(display, cpu_transcoder),
> > TRANS_PUSH_EN,
> > +                    0);
> >  
> >         if (HAS_AS_SDP(display))
> >                 intel_de_write(display,
> > -- 
> > 2.34.1
>