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

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Message-ID: <5f968f2a-012c-4b39-af78-1eafa483c9a0@tuxon.dev>
Date: Fri, 30 Aug 2024 17:41:53 +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 17:26, Geert Uytterhoeven wrote:
> 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().

Ah, I see. That can be done. Sorry for confusion.

Thank you,
Claudiu Beznea

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