[PATCH v3 4/5] drm/panfrost: devfreq: set opp to the recommended one to configure and enable regulator

[Biju Das]

Hi Clement,

> Subject: Re: [PATCH v3 4/5] drm/panfrost: devfreq: set opp to the
> recommended one to configure and enable regulator
> 
> Hi Biju,
> 
> On Tue, 6 Sept 2022 at 08:42, Biju Das <biju.das.jz at bp.renesas.com>
> wrote:
> >
> > Hi Clement,
> >
> > >
> > > Hi,
> > >
> > > On Mon, 5 Sept 2022 at 20:17, Biju Das <biju.das.jz at bp.renesas.com>
> > > wrote:
> > > >
> > > > Hi,
> > > >
> > > > Thanks for the patch.
> > > >
> > > > > Subject: [PATCH v3 4/5] drm/panfrost: devfreq: set opp to the
> > > > > recommended one to configure and enable regulator
> > > > >
> > > > > devm_pm_opp_set_regulators() doesn't enable regulator, which
> > > > > make regulator framework switching it off during
> regulator_late_cleanup().
> > > >
> > > > In that case, why not regulator_get()for Dynamic regulator(non
> > > > fixed regulator)??
> > >
> > > Sorry I don't understand, what do you mean?
> >
> > Normally we need to turn on regulator and clock only when needed.
> > I am not sure with your new code, will make it always on and drains
> > the power unnecessarily and does it set lower opp or higher opp at the
> > start??
> 
> The code doesn't make it always on, it makes it how it should be at the
> recommended OPP which is the "start point".
> 
> If the recommended OPP says to switch off the regulator then it will.
> 
> >
> > Compared to the fixed regulator, you have voltage regulator to control
> > that is the difference between my environment and Your environment.
> >
> > I am not sure any other SoC is using voltage regulator??
> > If yes, thenthere should be some bug or some difference in HW which is
> > giving different behaviour??
> >
> > If you are the first one using voltage regulator with mali gpu, Then
> > Your implementation may be correct, as you have proper HW to check.
> 
> The issue is that my regulator is not marked as "always-on", if no OPP is
> called before regulator_late_cleanup() then nobody sets the
> regulator_enable() and the regulator is switched off, which makes my
> board hang.

Cool, From your testing looks like no one tested this feature with
mali GPU on mainline??

Cheers,
Biju


> 
> Like Viresh recommends I will send an update with more details in the
> commit log.
> 
> Regards,
> Clement
> 
> 
> >
> > >
> > > >
> > > > >
> > > > > Call dev_pm_opp_set_opp() with the recommend OPP in
> > > > > panfrost_devfreq_init() to enable the regulator and avoid any
> > > > > switch off by regulator_late_cleanup().
> > > > >
> > > > > Suggested-by: Viresh Kumar <viresh.kumar at linaro.org>
> > > > > Signed-off-by: Clément Péron <peron.clem at gmail.com>
> > > > > ---
> > > > >  drivers/gpu/drm/panfrost/panfrost_devfreq.c | 8 ++++++++
> > > > >  1 file changed, 8 insertions(+)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> > > > > b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> > > > > index 5110cd9b2425..67b242407156 100644
> > > > > --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> > > > > +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
> > > > > @@ -131,6 +131,14 @@ int panfrost_devfreq_init(struct
> > > > > panfrost_device
> > > > > *pfdev)
> > > > >               return PTR_ERR(opp);
> > > > >
> > > > >       panfrost_devfreq_profile.initial_freq = cur_freq;
> > > > > +
> > > > > +     /* Setup and enable regulator */
> > > > > +     ret = dev_pm_opp_set_opp(dev, opp);
> > > > > +     if (ret) {
> > > > > +             DRM_DEV_ERROR(dev, "Couldn't set recommended
> OPP\n");
> > > > > +             return ret;
> > > > > +     }
> > > >
> > > >
> > > > FYI,
> > > > On RZ/G2L mali gpu, we have fixed regulator and I was able to do
> > > > GPU OPP transition without any issues previously.
> > >
> > > rzg2l-smarc-som.dtsi uses regulator reg_1p1v; which is marked as
> > > regulator-always-on; that's why
> > > regulator_late_cleanup() doesn't switch it off.
> >
> > Yes that is correct. It is fixed regulator and always on.
> > We control only frequency.
> >
> > Cheers,
> > Biju
> >
> > >
> > > >
> > > > root at smarc-rzg2l:~# cat /sys/class/devfreq/11840000.gpu/trans_stat
> > > >      From  :   To
> > > >            :  50000000  62500000 100000000 125000000 200000000
> > > 250000000 400000000 500000000   time(ms)
> > > > *  50000000:         0         0         0         0         0
> > > 0         0         1       144
> > > >    62500000:         0         0         0         0         0
> > > 0         0         0         0
> > > >   100000000:         0         0         0         0         0
> > > 0         0         9       524
> > > >   125000000:         0         0         9         0         0
> > > 0         0         3      2544
> > > >   200000000:         0         0         0        11         0
> > > 0         0        46      3304
> > > >   250000000:         1         0         0         0        33
> > > 0         0         0      7496
> > > >   400000000:         0         0         0         0        16
> > > 19         0         0      2024
> > > >   500000000:         1         0         0         1         8
> > > 15        35         0      4032
> > > > Total transition : 208
> > > >
> > > > Cheers,
> > > > Biju
> > > >