Re: [PATCH 3/4] drm/panfrost: Implement ability to turn on/off regulators in suspend

[AngeloGioacchino Del Regno]

Il 30/10/23 15:57, Steven Price ha scritto:
> On 30/10/2023 13:22, AngeloGioacchino Del Regno wrote:
> > Some platforms/SoCs can power off the GPU entirely by completely cutting
> > off power, greatly enhancing battery time during system suspend: add a
> > new pm_feature GPU_PM_VREG_OFF to allow turning off the GPU regulators
> > during full suspend only on selected platforms.
> >
> > Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/panfrost/panfrost_device.c | 19 ++++++++++++++++++-
> >   drivers/gpu/drm/panfrost/panfrost_device.h |  2 ++
> >   2 files changed, 20 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
> > index 2022ed76a620..51b22eb0971d 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_device.c
> > +++ b/drivers/gpu/drm/panfrost/panfrost_device.c
> > @@ -431,10 +431,21 @@ static int panfrost_device_resume(struct device *dev)
> >   	struct panfrost_device *pfdev = dev_get_drvdata(dev);
> >   	int ret;
> >   
> > +	if (pfdev->comp->pm_features & BIT(GPU_PM_VREG_OFF)) {
> > +		unsigned long freq = pfdev->pfdevfreq.fast_rate;
> > +		struct dev_pm_opp *opp;
> > +
> > +		opp = dev_pm_opp_find_freq_ceil(dev, &freq);
> > +		if (IS_ERR(opp))
> > +			return PTR_ERR(opp);
> > +		dev_pm_opp_put(opp);
> > +		dev_pm_opp_set_opp(dev, opp);
>
> These lines look the wrong way round - surely we want to hang onto the
> reference until the set_opp call is made?

Whoops! Yes, thanks, this happened during a cleanup for whatever reason.
I'll invert those for v2.

Angelo

> Steve
>
> > +	}
> > +
> >   	if (pfdev->comp->pm_features & BIT(GPU_PM_CLK_DIS)) {
> >   		ret = clk_enable(pfdev->clock);
> >   		if (ret)
> > -			return ret;
> > +			goto err_clk;
> >   
> >   		if (pfdev->bus_clock) {
> >   			ret = clk_enable(pfdev->bus_clock);
> > @@ -455,6 +466,9 @@ static int panfrost_device_resume(struct device *dev)
> >   err_bus_clk:
> >   	if (pfdev->comp->pm_features & BIT(GPU_PM_CLK_DIS))
> >   		clk_disable(pfdev->clock);
> > +err_clk:
> > +	if (pfdev->comp->pm_features & BIT(GPU_PM_VREG_OFF))
> > +		dev_pm_opp_set_opp(dev, NULL);
> >   	return ret;
> >   }
> >   
> > @@ -474,6 +488,9 @@ static int panfrost_device_suspend(struct device *dev)
> >   			clk_disable(pfdev->bus_clock);
> >   	}
> >   
> > +	if (pfdev->comp->pm_features & BIT(GPU_PM_VREG_OFF))
> > +		dev_pm_opp_set_opp(dev, NULL);
> > +
> >   	return 0;
> >   }
> >   
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
> > index d7f179eb8ea3..0fc558db6bfd 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_device.h
> > +++ b/drivers/gpu/drm/panfrost/panfrost_device.h
> > @@ -28,9 +28,11 @@ struct panfrost_perfcnt;
> >   /**
> >    * enum panfrost_gpu_pm - Supported kernel power management features
> >    * @GPU_PM_CLK_DIS:  Allow disabling clocks during system suspend
> > + * @GPU_PM_VREG_OFF: Allow turning off regulators during system suspend
> >    */
> >   enum panfrost_gpu_pm {
> >   	GPU_PM_CLK_DIS,
> > +	GPU_PM_VREG_OFF,
> >   };
> >   
> >   struct panfrost_features {
>
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