[RFC 5/6] drm/xe/pm: D3Cold target state

[Ville Syrjälä]

On Tue, Feb 25, 2025 at 06:00:04PM +0000, Gupta, Anshuman wrote:
> 
> 
> > -----Original Message-----
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Sent: Tuesday, February 25, 2025 11:20 PM
> > To: Gupta, Anshuman <anshuman.gupta at intel.com>
> > Cc: intel-xe at lists.freedesktop.org; linux-acpi at vger.kernel.org; linux-
> > pci at vger.kernel.org; rafael at kernel.org; lenb at kernel.org;
> > bhelgaas at google.com; ilpo.jarvinen at linux.intel.com; De Marchi, Lucas
> > <lucas.demarchi at intel.com>; Vivi, Rodrigo <rodrigo.vivi at intel.com>; Nilawar,
> > Badal <badal.nilawar at intel.com>; Nasim, Kam <kam.nasim at intel.com>
> > Subject: Re: [RFC 5/6] drm/xe/pm: D3Cold target state
> > 
> > On Mon, Feb 24, 2025 at 10:18:48PM +0530, Anshuman Gupta wrote:
> > > Trade-off D3Cold target state based upon current vram usages.
> > > if vram usages is greater than vram_d3cold_threshold and GPU has
> > > display connected
> > 
> > Why would anyone care about displays being connected or not?
> As per specs we got to enable vrsr only when there is display connected,

What specs? And why do they say connected displays should be
a factor here?

I think the only thing that makes any sense for this kind of stuff
would be sysfs power/ knobs that allow the system administrator to
tune the behaviour for their specific use case. And if no such knobs
exist currently then perhaps they should be added.

> We can check that in probe but a drm connector status can change after completion of probe. That is the reason to put a check for display connected in idle callback.
> Thanks,
> Anshuman
> > 
> > > then target D3Cold state is D3Cold-VRSR otherwise target state is
> > > D3COLD-Off.
> > >
> > > Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
> > > ---
> > >  drivers/gpu/drm/xe/display/xe_display.c | 22 ++++++++++++++++++++++
> > > drivers/gpu/drm/xe/display/xe_display.h |  1 +
> > >  drivers/gpu/drm/xe/xe_pm.c              | 12 ++++++++++++
> > >  3 files changed, 35 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/xe/display/xe_display.c
> > > b/drivers/gpu/drm/xe/display/xe_display.c
> > > index 02a413a07382..140a43d6b1b6 100644
> > > --- a/drivers/gpu/drm/xe/display/xe_display.c
> > > +++ b/drivers/gpu/drm/xe/display/xe_display.c
> > > @@ -548,3 +548,25 @@ int xe_display_probe(struct xe_device *xe)
> > >  	unset_display_features(xe);
> > >  	return 0;
> > >  }
> > > +
> > > +bool xe_display_connected(struct xe_device *xe) {
> > > +	struct drm_connector *list_connector;
> > > +	struct drm_connector_list_iter iter;
> > > +	bool ret = false;
> > > +
> > > +	mutex_lock(&xe->drm.mode_config.mutex);
> > > +	drm_connector_list_iter_begin(&xe->drm, &iter);
> > > +
> > > +	drm_for_each_connector_iter(list_connector, &iter) {
> > > +		if (list_connector->status == connector_status_connected) {
> > > +			ret = true;
> > > +			break;
> > > +		}
> > > +	}
> > > +
> > > +	drm_connector_list_iter_end(&iter);
> > > +	mutex_unlock(&xe->drm.mode_config.mutex);
> > > +
> > > +	return ret;
> > > +}
> > > diff --git a/drivers/gpu/drm/xe/display/xe_display.h
> > > b/drivers/gpu/drm/xe/display/xe_display.h
> > > index 685dc74402fb..c6bc54323084 100644
> > > --- a/drivers/gpu/drm/xe/display/xe_display.h
> > > +++ b/drivers/gpu/drm/xe/display/xe_display.h
> > > @@ -40,6 +40,7 @@ void xe_display_pm_resume(struct xe_device *xe);
> > > void xe_display_pm_runtime_suspend(struct xe_device *xe);  void
> > > xe_display_pm_runtime_suspend_late(struct xe_device *xe);  void
> > > xe_display_pm_runtime_resume(struct xe_device *xe);
> > > +bool xe_display_connected(struct xe_device *xe);
> > >
> > >  #else
> > >
> > > diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
> > > index 81e67b5693dc..6d28aedcb062 100644
> > > --- a/drivers/gpu/drm/xe/xe_pm.c
> > > +++ b/drivers/gpu/drm/xe/xe_pm.c
> > > @@ -198,6 +198,14 @@ static void xe_rpm_lockmap_release(const struct
> > xe_device *xe)
> > >  			 &xe_pm_runtime_d3cold_map);
> > >  }
> > >
> > > +static void xe_pm_suspend_prepare(struct xe_device *xe) {
> > > +	if (pm_suspend_target_state == PM_SUSPEND_TO_IDLE)
> > > +		xe_pm_d3cold_allowed_toggle(xe);
> > > +	else
> > > +		xe->d3cold.allowed = XE_D3COLD_OFF; }
> > > +
> > >  /**
> > >   * xe_pm_suspend - Helper for System suspend, i.e. S0->S3 / S0->S2idle
> > >   * @xe: xe device instance
> > > @@ -213,6 +221,8 @@ int xe_pm_suspend(struct xe_device *xe)
> > >  	drm_dbg(&xe->drm, "Suspending device\n");
> > >  	trace_xe_pm_suspend(xe, __builtin_return_address(0));
> > >
> > > +	xe_pm_suspend_prepare(xe);
> > > +
> > >  	err = xe_pxp_pm_suspend(xe->pxp);
> > >  	if (err)
> > >  		goto err;
> > > @@ -875,6 +885,8 @@ void xe_pm_d3cold_allowed_toggle(struct
> > xe_device
> > > *xe)
> > >
> > >  	if (total_vram_used_mb < xe->d3cold.vram_threshold)
> > >  		xe->d3cold.allowed = XE_D3COLD_OFF;
> > > +	else if (xe->d3cold.vrsr_capable && xe_display_connected(xe))
> > > +		xe->d3cold.allowed = XE_D3COLD_VRSR;
> > >  	else
> > >  		xe->d3cold.allowed = XE_D3HOT;
> > >
> > > --
> > > 2.34.1
> > 
> > --
> > Ville Syrjälä
> > Intel

-- 
Ville Syrjälä
Intel