Re: [PATCH 20/35] drm/i915/vrr: Avoid sending PUSH when VRR TG is used with Fixed refresh rate

["Nautiyal, Ankit K" <ankit.k.nautiyal@xxxxxxxxx>]

On 1/25/2025 2:42 AM, Ville Syrjälä wrote:
> On Fri, Jan 24, 2025 at 08:30:05PM +0530, Ankit Nautiyal wrote:
> > As per the spec, the PUSH enable must be set if not configuring for a
> > fixed refresh rate (i.e Vmin == Flipline == Vmax is not true).
> >
> > v2: Use helper intel_vrr_use_push(). (Ville)
> > v3: directly use the condition, instead of checking for VRR mode.
> >
> > Bspec: 68925
> > Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
> > Reviewed-by: Mitul Golani <mitulkumar.ajitkumar.golani@xxxxxxxxx> (v1)
> > ---
> >   drivers/gpu/drm/i915/display/intel_vrr.c | 14 ++++++++++----
> >   1 file changed, 10 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
> > index 65bbe40881d6..34e44cd52353 100644
> > --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> > @@ -437,13 +437,18 @@ void intel_vrr_set_transcoder_timings(const struct intel_crtc_state *crtc_state)
> >   			       VRR_VSYNC_START(crtc_state->vrr.vsync_start));
> >   }
> >   
> > +static bool intel_vrr_use_push(const struct intel_crtc_state *crtc_state)
> > +{
> > +	return crtc_state->vrr.flipline != crtc_state->vrr.vmax;
> > +}
> > +
> >   void intel_vrr_send_push(struct intel_dsb *dsb,
> >   			 const struct intel_crtc_state *crtc_state)
> >   {
> >   	struct intel_display *display = to_intel_display(crtc_state);
> >   	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
> >   
> > -	if (!intel_vrrtg_is_enabled(crtc_state))
> > +	if (!intel_vrr_use_push(crtc_state))
> >   		return;
> >   
> >   	if (dsb)
> > @@ -462,7 +467,7 @@ bool intel_vrr_is_push_sent(const struct intel_crtc_state *crtc_state)
> >   	struct intel_display *display = to_intel_display(crtc_state);
> >   	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
> >   
> > -	if (!intel_vrrtg_is_enabled(crtc_state))
> > +	if (!intel_vrr_use_push(crtc_state))
> >   		return false;
> >   
> >   	return intel_de_read(display, TRANS_PUSH(display, cpu_transcoder)) & TRANS_PUSH_SEND;
> > @@ -476,8 +481,9 @@ void intel_vrr_enable(const struct intel_crtc_state *crtc_state)
> >   	if (!intel_vrrtg_is_enabled(crtc_state))
> >   		return;
> >   
> > -	intel_de_write(display, TRANS_PUSH(display, cpu_transcoder),
> > -		       TRANS_PUSH_EN);
> > +	if (intel_vrr_use_push(crtc_state))
> > +		intel_de_write(display, TRANS_PUSH(display, cpu_transcoder),
> > +			       TRANS_PUSH_EN);
> What I saw on TGL and ADL is that if you don't enable PUSH then nothing
> works. So I think we just want to have this enabled whenever the VRR
> timing generator is enabled.


Then perhaps I'll drop this patch, or should we have a specific check 
for TGL/ADL (though we are not enabling fixed refresh rate on these as yet).

Regards,

Ankit

> >   
> >   	if (crtc_state->vrr.mode == INTEL_VRRTG_MODE_CMRR) {
> >   		intel_de_write(display, TRANS_VRR_CTL(display, cpu_transcoder),
> > --
> > 2.45.2