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

[Geert Uytterhoeven]

Hi Peng,

On Tue, Apr 23, 2024 at 9:35 AM Peng Fan <peng.fan@xxxxxxx> wrote:
> > Subject: Re: [PATCH] serial: sh-sci: Call device_set_wakeup_path() for serial
> > console
> > CC Peng
>
> Thanks for Ccing me, but I am not familiar with sh-sci driver (:

But you are with the IMX pmdomain driver, so please read on ;-)

> > 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
> > > durring system suspend. Otherwise, the SCI power domain is turned off,
> > > 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>

> > > --- 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-m68korg

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