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Date: Tue, 6 Sep 2022 10:08:18 +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 Tue, 6 Sept 2022 at 10:06, Biju Das <biju.das.jz@...renesas.com> wrote:
>
> 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@...renesas.com>
> > wrote:
> > >
> > > Hi Clement,
> > >
> > > >
> > > > 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?
> > >
> > > 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??
Or no one without always-on.
Clement
>
> 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@...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.
> > >
> > > Yes that is correct. It is fixed regulator and always on.
> > > We control only frequency.
> > >
> > > Cheers,
> > > Biju
> > >
> > > >
> > > > >
> > > > > 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
> > > > >
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