linux-kernel - Re: [PATCH] serial: sh-sci: Call device_set_wakeup

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Date: Tue, 23 Apr 2024 15:10:50 +0300
From: claudiu beznea <claudiu.beznea@...on.dev>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: gregkh@...uxfoundation.org, jirislaby@...nel.org, ulf.hansson@...aro.org,
 linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
 linux-pm@...r.kernel.org, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH] serial: sh-sci: Call device_set_wakeup_path() for serial
 console

Hi, Geert,

On 23.04.2024 10:27, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> CC Peng
> 
> Thanks for your patch!
> 
> On Mon, Apr 22, 2024 at 1:11 PM Claudiu <claudiu.beznea@...on.dev> wrote:
>> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>>
>> In case the SCI is used as a UART console, no_console_suspend is
>> available in bootargs and SCI is part of a software-controlled power
>> domain we need to call device_set_wakeup_path(). This lets the power
>> domain core code knows that this domain should not be powered off
> 
> know
> 
>> durring system suspend. Otherwise, the SCI power domain is turned off,
> 
> during
> 
>> nothing is printed while suspending and the suspend/resume process is
>> blocked. This was detected on the RZ/G3S SoC while adding support
>> for power domains.
>>
>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>> ---
>>  drivers/tty/serial/sh-sci.c | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
>> index 97031db26ae4..57a7f18e16e4 100644
>> --- a/drivers/tty/serial/sh-sci.c
>> +++ b/drivers/tty/serial/sh-sci.c
>> @@ -3441,8 +3441,12 @@ static __maybe_unused int sci_suspend(struct device *dev)
>>  {
>>         struct sci_port *sport = dev_get_drvdata(dev);
>>
>> -       if (sport)
>> +       if (sport) {
>> +               if (uart_console(&sport->port) && !console_suspend_enabled)
>> +                       device_set_wakeup_path(dev);
> 
> device_set_awake_path(), as of commit 10bb4e4ab7dd3898 ("PM: sleep:
> Add helpers to allow a device to remain powered-on") in v6.6
> (although I'm still a bit puzzled about the difference).

Ok, I wasn't aware of it. I'll switch to this one.

> 
>> +
>>                 uart_suspend_port(&sci_uart_driver, &sport->port);
> 
> I think it would be better to make this more general, and move the call
> to the existing console_suspend_enabled handling in uart_suspend_port().

Ok, I'll try this way.

> 
>> +       }
>>
>>         return 0;
>>  }
> 
> If this works, we can remove the console_suspend_enabled handling
> from drivers/pmdomain/renesas/rmobile-sysc.c, and revert commit
> 309864dcf92b76fc ("genpd: imx: scu-pd: do not power off console if
> no_console_suspend").

OK, first I'll go with this patch and after things settles down with it
I'll propose changes for rmobile-sysc and imx. Is this ok for you?

Thank you,
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