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

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Date:   Mon, 5 Sep 2022 21:39:29 +0200
From:   Clément Péron <peron.clem@...il.com>
To:     Biju Das <biju.das.jz@...renesas.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Steven Price <steven.price@....com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Bjorn Andersson <andersson@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Arnd Bergmann <arnd@...db.de>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        Vinod Koul <vkoul@...nel.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Rob Herring <robh@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-sunxi@...ts.linux.dev" <linux-sunxi@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Subject: Re: [PATCH v3 4/5] drm/panfrost: devfreq: set opp to the recommended
 one to configure and enable regulator

Hi,

On Mon, 5 Sept 2022 at 20:17, Biju Das <biju.das.jz@...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?

>
> >
> > 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@...aro.org>
> > Signed-off-by: Clément Péron <peron.clem@...il.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.

Regards,
Clement

>
> root@...rc-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
>