RE: [PATCH] serial: sh-sci: Call device_set_wakeup_path() for serial console

[Peng Fan]

Hi Geert,

> Subject: Re: [PATCH] serial: sh-sci: Call device_set_wakeup_path() for serial
> console
> 
> Hi Claudiu,
> 
> CC Peng

Thanks for Ccing me, but I am not familiar with sh-sci driver (:

Thanks,
Peng.
> 
> Thanks for your patch!
> 
> On Mon, Apr 22, 2024 at 1:11 PM Claudiu <claudiu.beznea@xxxxxxxxx>
> wrote:
> > From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxxx>
> > ---
> >  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).
> 
> > +
> >                 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().
> 
> > +       }
> >
> >         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").
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-
> 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