linux-kernel - Re: [PATCH 10/15] drm/panfrost: add regulators to devfreq

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Date:   Fri, 29 May 2020 14:37:04 +0200
From:   Clément Péron <peron.clem@...il.com>
To:     Steven Price <steven.price@....com>
Cc:     Rob Herring <robh@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 10/15] drm/panfrost: add regulators to devfreq

Hi Steven,

On Thu, 28 May 2020 at 15:23, Steven Price <steven.price@....com> wrote:
>
> On 10/05/2020 17:55, Clément Péron wrote:
> > Some OPP tables specify voltage for each frequency. Devfreq can
> > handle these regulators but they should be get only 1 time to avoid
> > issue and know who is in charge.
> >
> > If OPP table is probe don't init regulator.
> >
> > Signed-off-by: Clément Péron <peron.clem@...il.com>
>
> This looks like it should work - thanks for doing this!

Yes but I'm not really happy how it's implemented.

Looks like a bit a workaround but didn't found a better solution.

Thanks for your review,
Clement

>
> Reviewed-by: Steven Price <steven.price@....com>
>
> > ---
> >   drivers/gpu/drm/panfrost/panfrost_devfreq.c | 19 +++++++++++++++++++
> >   drivers/gpu/drm/panfrost/panfrost_devfreq.h |  2 ++
> >   drivers/gpu/drm/panfrost/panfrost_device.c  | 11 +++++++----
> >   3 files changed, 28 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> > index fce21c682414..9ffea0d4a087 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> > +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> > @@ -93,6 +93,7 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
> >       unsigned long cur_freq;
> >       struct device *dev = &pfdev->pdev->dev;
> >       struct devfreq *devfreq;
> > +     struct opp_table *opp_table;
> >       struct thermal_cooling_device *cooling;
> >       struct panfrost_devfreq *pfdevfreq = &pfdev->pfdevfreq;
> >
> > @@ -102,6 +103,19 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
> >
> >       spin_lock_init(&pfdevfreq->lock);
> >
> > +     opp_table = dev_pm_opp_set_regulators(dev, pfdev->comp->supply_names,
> > +                                           pfdev->comp->num_supplies);
> > +     if (IS_ERR(opp_table)) {
> > +             ret = PTR_ERR(opp_table);
> > +             /* Continue if the optional regulator is missing */
> > +             if (ret != -ENODEV) {
> > +                     DRM_DEV_ERROR(dev, "Couldn't set OPP regulators\n");
> > +                     goto err_fini;
> > +             }
> > +     } else {
> > +             pfdevfreq->regulators_opp_table = opp_table;
> > +     }
> > +
> >       ret = dev_pm_opp_of_add_table(dev);
> >       if (ret) {
> >               DRM_DEV_ERROR(dev, "Couldn't add OPP table\n");
> > @@ -157,6 +171,11 @@ void panfrost_devfreq_fini(struct panfrost_device *pfdev)
> >               dev_pm_opp_of_remove_table(&pfdev->pdev->dev);
> >               pfdevfreq->opp_of_table_added = false;
> >       }
> > +
> > +     if (pfdevfreq->regulators_opp_table) {
> > +             dev_pm_opp_put_regulators(pfdevfreq->regulators_opp_table);
> > +             pfdevfreq->regulators_opp_table = NULL;
> > +     }
> >   }
> >
> >   void panfrost_devfreq_resume(struct panfrost_device *pfdev)
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.h b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> > index add203cb00c2..347cde4786cf 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> > +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.h
> > @@ -8,12 +8,14 @@
> >   #include <linux/ktime.h>
> >
> >   struct devfreq;
> > +struct opp_table;
> >   struct thermal_cooling_device;
> >
> >   struct panfrost_device;
> >
> >   struct panfrost_devfreq {
> >       struct devfreq *devfreq;
> > +     struct opp_table *regulators_opp_table;
> >       struct thermal_cooling_device *cooling;
> >       bool opp_of_table_added;
> >
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
> > index 67eedf64e82d..8b17fb2e3369 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_device.c
> > +++ b/drivers/gpu/drm/panfrost/panfrost_device.c
> > @@ -222,10 +222,13 @@ int panfrost_device_init(struct panfrost_device *pfdev)
> >               goto err_out0;
> >       }
> >
> > -     err = panfrost_regulator_init(pfdev);
> > -     if (err) {
> > -             dev_err(pfdev->dev, "regulator init failed %d\n", err);
> > -             goto err_out1;
> > +     /* OPP will handle regulators */
> > +     if (!pfdev->pfdevfreq.opp_of_table_added) {
> > +             err = panfrost_regulator_init(pfdev);
> > +             if (err) {
> > +                     dev_err(pfdev->dev, "regulator init failed %d\n", err);
> > +                     goto err_out1;
> > +             }
> >       }
> >
> >       err = panfrost_reset_init(pfdev);
> >
>