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

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Message-ID: <8b6fc67d-5e07-4403-ac07-6ad0b9d61882@tuxon.dev>
Date: Fri, 30 Aug 2024 10:46:28 +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 29.08.2024 15:32, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> 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>
> 
> Thanks for your patch!
> 
>> --- a/drivers/clk/renesas/rzg2l-cpg.c
>> +++ b/drivers/clk/renesas/rzg2l-cpg.c
>> @@ -1680,11 +1680,13 @@ static int rzg2l_cpg_power_off(struct generic_pm_domain *domain)
>>         return 0;
>>  }
>>
>> -static int __init rzg2l_cpg_pd_setup(struct rzg2l_cpg_pd *pd, bool always_on)
>> +static int __init rzg2l_cpg_pd_setup(struct rzg2l_cpg_pd *pd, u32 genpd_flags,
>> +                                    bool always_on)
> 
> You don't need always_on, as that should already be reflected in
> genpd_flags.

OK.

> 
> Also, you could do without passing genpd_flags, if the caller would have
> initialized pd->genpd.flags (it already initializes pd->genpd.name).

That could be done, indeed.

> 
>>  {
>>         struct dev_power_governor *governor;
>>
>> -       pd->genpd.flags |= GENPD_FLAG_PM_CLK | GENPD_FLAG_ACTIVE_WAKEUP;
>> +       pd->genpd.flags |= GENPD_FLAG_PM_CLK | GENPD_FLAG_ACTIVE_WAKEUP |
>> +                          genpd_flags;
> 
> Change not needed if the caller would have initialized flags.

OK

> 
>>         pd->genpd.attach_dev = rzg2l_cpg_attach_dev;
>>         pd->genpd.detach_dev = rzg2l_cpg_detach_dev;
>>         if (always_on) {
> 
> The next line is
> 
>     pd->genpd.flags |= GENPD_FLAG_ALWAYS_ON;
> 
> which should already be the case if always_on is true, so it can
> be removed.

OK

> 
>> @@ -1712,7 +1714,7 @@ static int __init rzg2l_cpg_add_clk_domain(struct rzg2l_cpg_priv *priv)
>>
>>         pd->genpd.name = np->name;
> 
> pd->genpd.flags = GENPD_FLAG_ALWAYS_ON;

Agree.

> 
>>         pd->priv = priv;
>> -       ret = rzg2l_cpg_pd_setup(pd, true);
>> +       ret = rzg2l_cpg_pd_setup(pd, 0, true);
> 
> s/0/GENPD_FLAG_ALWAYS_ON/, FWIW ;-)
> 
>>         if (ret)
>>                 return ret;
>>
>> @@ -1777,7 +1779,8 @@ static int __init rzg2l_cpg_add_pm_domains(struct rzg2l_cpg_priv *priv)
>>                 return ret;
>>
>>         for (unsigned int i = 0; i < info->num_pm_domains; i++) {
>> -               bool always_on = !!(info->pm_domains[i].flags & RZG2L_PD_F_ALWAYS_ON);
>> +               u32 genpd_flags = info->pm_domains[i].genpd_flags;
>> +               bool always_on = !!(genpd_flags & GENPD_FLAG_ALWAYS_ON);
>>                 struct rzg2l_cpg_pd *pd;
>>
>>                 pd = devm_kzalloc(dev, sizeof(*pd), GFP_KERNEL);
>> @@ -1789,7 +1792,7 @@ static int __init rzg2l_cpg_add_pm_domains(struct rzg2l_cpg_priv *priv)
> 
> You can add
> 
>     pd->genpd.flags = info->pm_domains[i].genpd_flags;
> 
> above.

OK

> 
>>                 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.

Thank you for your review,
Claudiu Beznea

> 
> 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