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

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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