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From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Tue, 23 Apr 2024 09:45:05 +0200
Message-ID: <CAMuHMdWvACWWSJUsaT9FYVN=VCzAjJpxmJJpK1h3CA_gbWKVsQ@mail.gmail.com>
Subject: Re: [PATCH] serial: sh-sci: Call device_set_wakeup_path() for serial console
To: Peng Fan <peng.fan@nxp.com>
Cc: Claudiu <claudiu.beznea@tuxon.dev>, 
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>, "jirislaby@kernel.org" <jirislaby@kernel.org>, 
	"ulf.hansson@linaro.org" <ulf.hansson@linaro.org>, 
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, 
	"linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>, 
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>
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Hi Peng,

On Tue, Apr 23, 2024 at 9:35=E2=80=AFAM Peng Fan <peng.fan@nxp.com> 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=E2=80=AFPM Claudiu <claudiu.beznea@tuxon.d=
ev>
> > wrote:
> > > From: Claudiu Beznea <claudiu.beznea.uj@bp.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
> > > 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@bp.renesas.com>

> > > --- 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 =3D dev_get_drvdata(dev);
> > >
> > > -       if (sport)
> > > +       if (sport) {
> > > +               if (uart_console(&sport->port) && !console_suspend_en=
abled)
> > > +                       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

--=20
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k=
org

In personal conversations with technical people, I call myself a hacker. Bu=
t
when I'm talking to journalists I just say "programmer" or something like t=
hat.
                                -- Linus Torvalds