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

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Message-ID: <194e87f4-7eab-4bfb-833a-27fabd2d5205@tuxon.dev>
Date: Fri, 30 Aug 2024 17:07:54 +0300
From: claudiu beznea <claudiu.beznea@...on.dev>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
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, Geert,

On 30.08.2024 11:06, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> 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.

Thank you,
Claudiu Beznea

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
>