linux-kernel - Re: [PATCH v2 1/3] clk: renesas: rzg2l-cpg: Use GENPD_FLAG

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Message-ID: <CAMuHMdWKVfUn5Xy+vxT3puNT+AKLZtm7o=QBysWxfjk434yUJA@mail.gmail.com>
Date: Fri, 30 Aug 2024 16:26:47 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: claudiu beznea <claudiu.beznea@...on.dev>
Cc: mturquette@...libre.com, sboyd@...nel.org, wim@...ux-watchdog.org, 
	linux@...ck-us.net, ulf.hansson@...aro.org, linux-renesas-soc@...r.kernel.org, 
	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-watchdog@...r.kernel.org, linux-pm@...r.kernel.org, 
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH v2 1/3] clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags
 instead of local ones

Hi Claudiu,

On Fri, Aug 30, 2024 at 4:07 PM claudiu beznea <claudiu.beznea@...on.dev> wrote:
> On 30.08.2024 11:06, Geert Uytterhoeven wrote:
> > On Fri, Aug 30, 2024 at 9:46 AM claudiu beznea <claudiu.beznea@...on.dev> wrote:
> >> On 29.08.2024 15:32, Geert Uytterhoeven wrote:
> >>> On Wed, Aug 28, 2024 at 4:06 PM Claudiu <claudiu.beznea@...on.dev> wrote:
> >>>> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> >>>>
> >>>> For watchdog PM domain it is necessary to provide GENPD_FLAG_IRQ_SAFE flag
> >>>> to be able to power on the watchdog PM domain from atomic context. For
> >>>> this, adjust the current infrastructure to be able to provide GENPD_FLAG_*
> >>>> for individual PM domains.
> >>>>
> >>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> >
> >>>> --- a/drivers/clk/renesas/rzg2l-cpg.c
> >>>> +++ b/drivers/clk/renesas/rzg2l-cpg.c
> >
> >>>
> >>>>                 pd->id = info->pm_domains[i].id;
> >>>>                 pd->priv = priv;
> >>>>
> >>>> -               ret = rzg2l_cpg_pd_setup(pd, always_on);
> >>>> +               ret = rzg2l_cpg_pd_setup(pd, genpd_flags, always_on);
> >>>>                 if (ret)
> >>>>                         return ret;
> >>>
> >>> What about moving the conditional call to rzg2l_cpg_power_on()
> >>> below to rzg2l_cpg_pd_setup()? Then this function no longer needs
> >>> the always_on flag.
> >>
> >> That could be done but I think it will involve an extra power on/power off
> >> cycle for the unused domains.
> >
> > Still only to be done for the always-on domain, of course.
> > Anyway, up to you.
>
> I checked your proposal. If unconditional power on is going to be done for
> all the registered domains it may happen to register domains for which
> there are no enabled nodes in device tree and thus the domains to remain on
> (because the driver enables it under the hood and the genpd core doesn't
> know about it).
>
> With unconditional power on and the current DTSes the following domains
> remain on after booting with r9a08g045s33-smarc.dtb:
> - sdhi2
> - i2c2
> - i2c3
>
> as the domains are registered and powered (while registered) but the nodes
> are not enabled in DT.

To make it clear: I did not suggest doing an unconditional power-on.
I merely suggested moving the conditional power-on from
rzg2l_cpg_add_pm_domains() to rzg2l_cpg_pd_setup().

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds