[Intel-gfx] [PATCH] drm/i915/lnl: Remove watchdog timers for PSR

[Kahola, Mika]

> -----Original Message-----
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Sent: Friday, October 6, 2023 3:29 PM
> To: Kahola, Mika <mika.kahola at intel.com>
> Cc: intel-gfx at lists.freedesktop.org
> Subject: Re: [Intel-gfx] [PATCH] drm/i915/lnl: Remove watchdog timers for PSR
> 
> On Fri, Oct 06, 2023 at 02:42:10PM +0300, Mika Kahola wrote:
> > Currently we are not using watchdog timers for PSR/PSR2.
> > The patch disables these timers so they are not in use.
> 
> I can't figure out what you're saying here. What bspec seems to be saying is that the max_sleep thing got nuked from the hw so we
> no longer need to mask it.

Well, my understanding was that we would need to remove these from the driver as these are irrelevant.

> 
> >
> > BSpec: 69895
> >
> > Signed-off-by: Mika Kahola <mika.kahola at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_psr.c | 24
> > +++++++++++++++++-------
> >  1 file changed, 17 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> > b/drivers/gpu/drm/i915/display/intel_psr.c
> > index 850b11f20285..13b58dceb2bf 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > @@ -672,11 +672,15 @@ static void hsw_activate_psr1(struct intel_dp *intel_dp)
> >  	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> >  	enum transcoder cpu_transcoder = intel_dp->psr.transcoder;
> >  	u32 max_sleep_time = 0x1f;
> > -	u32 val = EDP_PSR_ENABLE;
> > +	u32 val = 0;
> >
> > -	val |= EDP_PSR_IDLE_FRAMES(psr_compute_idle_frames(intel_dp));
> >
> > -	val |= EDP_PSR_MAX_SLEEP_TIME(max_sleep_time);
> > +	if (DISPLAY_VER(dev_priv) < 20) {
> > +		val =  EDP_PSR_ENABLE;
> 
> That would mean you never enable PSR1 on lnl+
> 
> > +		val |= EDP_PSR_MAX_SLEEP_TIME(max_sleep_time);
> > +	}
> > +
> > +	val |= EDP_PSR_IDLE_FRAMES(psr_compute_idle_frames(intel_dp));
> >  	if (IS_HASWELL(dev_priv))
> >  		val |= EDP_PSR_MIN_LINK_ENTRY_TIME_8_LINES;
> >
> > @@ -1398,10 +1402,16 @@ static void intel_psr_enable_source(struct intel_dp *intel_dp,
> >  	 * runtime_pm besides preventing  other hw tracking issues now we
> >  	 * can rely on frontbuffer tracking.
> >  	 */
> > -	mask = EDP_PSR_DEBUG_MASK_MEMUP |
> > -	       EDP_PSR_DEBUG_MASK_HPD |
> > -	       EDP_PSR_DEBUG_MASK_LPSP |
> > -	       EDP_PSR_DEBUG_MASK_MAX_SLEEP;
> > +	if (DISPLAY_VER(dev_priv) >= 20)
> > +		mask = EDP_PSR_DEBUG_MASK_MEMUP |
> > +		       EDP_PSR_DEBUG_MASK_HPD |
> > +		       EDP_PSR_DEBUG_MASK_LPSP;
> > +	else
> > +		mask = EDP_PSR_DEBUG_MASK_MEMUP |
> > +		       EDP_PSR_DEBUG_MASK_HPD |
> > +		       EDP_PSR_DEBUG_MASK_LPSP |
> > +		       EDP_PSR_DEBUG_MASK_MAX_SLEEP;
> 
> The hpd mask bit also seems gone now, though there is no explanation why it disappeared.
> 
> > +
> >
> >  	/*
> >  	 * No separate pipe reg write mask on hsw/bdw, so have to unmask all
> > --
> > 2.34.1
> 
> --
> Ville Syrjälä
> Intel