Re: [PATCH 2/2] drm/panfrost: add devfreq regulator support

["Clément Péron" <peron.clem@gmail.com>]

Hi,

On Mon, 13 Apr 2020 at 16:18, Clément Péron <peron.clem@gmail.com> wrote:
>
> Hi Steven,
>
> On Mon, 13 Apr 2020 at 15:18, Steven Price <steven.price@arm.com> wrote:
> >
> > On 11/04/2020 21:06, Clément Péron wrote:
> > > OPP table can defined both frequency and voltage.
> > >
> > > Register the mali regulator if it exist.
> > >
> > > Signed-off-by: Clément Péron <peron.clem@gmail.com>
> > > ---
> > >   drivers/gpu/drm/panfrost/panfrost_devfreq.c | 34 ++++++++++++++++++---
> > >   drivers/gpu/drm/panfrost/panfrost_device.h  |  1 +
> > >   2 files changed, 31 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> > > index 62541f4edd81..2dc8e2355358 100644
> > > --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> > > +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> > > @@ -78,12 +78,26 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
> > >       struct device *dev = &pfdev->pdev->dev;
> > >       struct devfreq *devfreq;
> > >       struct thermal_cooling_device *cooling;
> > > +     const char *mali = "mali";
> > > +     struct opp_table *opp_table = NULL;
> > > +
> > > +     /* Regulator is optional */
> > > +     opp_table = dev_pm_opp_set_regulators(dev, &mali, 1);
> >
> > This looks like it applies before 3e1399bccf51 ("drm/panfrost: Add
> > support for multiple regulators") which is currently in drm-misc-next
> > (and linux-next). You want something more like:
>
> Thanks for you review, indeed I didn't see that multiple regulators
> support has been added.
> Will update in v2.
>
> >
> >      opp_table = dev_pm_opp_set_regulators(dev,
> >                                            pfdev->comp->supply_names,
> >                                            pfdev->comp->num_supplies);
> >
> > Otherwise a platform with multiple regulators won't work correctly.
> >
> > Also running on my firefly (RK3288) board I get the following warning:
> >
> >     debugfs: Directory 'ffa30000.gpu-mali' with parent 'vdd_gpu' already
> > present!
> >
> > This is due to the regulator debugfs entries getting created twice (once
> > in panfrost_regulator_init() and once here).
>
> Is it a warning that should be consider as an error? Look's more an info no?
> What should be the correct behavior if a device want to register two
> times the same regulator?

Or we can change the name from vdd_XXX to opp_vdd_XXX ?
https://elixir.bootlin.com/linux/latest/source/drivers/opp/debugfs.c#L45

>
> Link to original discussion:
> https://lore.kernel.org/patchwork/patch/1176717/
>
> Thanks,
> Clement
>
> >
> > I have been taking a look at doing the same thing (I picked up Martin
> > Blumenstingl's patch series[1]), but haven't had much time to focus on
> > this recently.
> >
> > Thanks,
> >
> > Steve
> >
> > [1]
> > https://lore.kernel.org/dri-devel/20200112001623.2121227-1-martin.blumenstingl@googlemail.com/
> >
> >
> > > +     if (IS_ERR(opp_table)) {
> > > +             ret = PTR_ERR(opp_table);
> > > +             if (ret != -ENODEV) {
> > > +                     DRM_DEV_ERROR(dev, "Failed to set regulator: %d\n", ret);
> > > +                     return ret;
> > > +             }
> > > +     }
> > > +     pfdev->devfreq.opp_table = opp_table;
> > >
> > >       ret = dev_pm_opp_of_add_table(dev);
> > > -     if (ret == -ENODEV) /* Optional, continue without devfreq */
> > > -             return 0;
> > > -     else if (ret)
> > > -             return ret;
> > > +     if (ret) {
> > > +             if (ret == -ENODEV) /* Optional, continue without devfreq */
> > > +                     ret = 0;
> > > +             goto err_opp_reg;
> > > +     }
> > >
> > >       panfrost_devfreq_reset(pfdev);
> > >
> > > @@ -119,6 +133,12 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
> > >   err_opp:
> > >       dev_pm_opp_of_remove_table(dev);
> > >
> > > +err_opp_reg:
> > > +     if (pfdev->devfreq.opp_table) {
> > > +             dev_pm_opp_put_regulators(pfdev->devfreq.opp_table);
> > > +             pfdev->devfreq.opp_table = NULL;
> > > +     }
> > > +
> > >       return ret;
> > >   }
> > >
> > > @@ -126,7 +146,13 @@ void panfrost_devfreq_fini(struct panfrost_device *pfdev)
> > >   {
> > >       if (pfdev->devfreq.cooling)
> > >               devfreq_cooling_unregister(pfdev->devfreq.cooling);
> > > +
> > >       dev_pm_opp_of_remove_table(&pfdev->pdev->dev);
> > > +
> > > +     if (pfdev->devfreq.opp_table) {
> > > +             dev_pm_opp_put_regulators(pfdev->devfreq.opp_table);
> > > +             pfdev->devfreq.opp_table = NULL;
> > > +     }
> > >   }
> > >
> > >   void panfrost_devfreq_resume(struct panfrost_device *pfdev)
> > > diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
> > > index 06713811b92c..f6b0c779dfe5 100644
> > > --- a/drivers/gpu/drm/panfrost/panfrost_device.h
> > > +++ b/drivers/gpu/drm/panfrost/panfrost_device.h
> > > @@ -86,6 +86,7 @@ struct panfrost_device {
> > >       struct {
> > >               struct devfreq *devfreq;
> > >               struct thermal_cooling_device *cooling;
> > > +             struct opp_table *opp_table;
> > >               ktime_t busy_time;
> > >               ktime_t idle_time;
> > >               ktime_t time_last_update;
> > >
> >
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