linux-kernel - Re: [PATCH] Input: hisi_powerkey: Enable system-wakeup for s2idle

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Message-ID: <CAPDyKFqp0874O500j1StQgVyr_fQud6eJTqzQW_GqEj49Yt6bA@mail.gmail.com>
Date: Wed, 12 Mar 2025 17:37:46 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: linux-input@...r.kernel.org, linux-kernel@...r.kernel.org, 
	"Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH] Input: hisi_powerkey: Enable system-wakeup for s2idle

On Tue, 11 Mar 2025 at 06:09, Dmitry Torokhov <dmitry.torokhov@...il.com> wrote:
>
> Hi Ulf,
>
> On Thu, Mar 06, 2025 at 12:50:21PM +0100, Ulf Hansson wrote:
> > To wake up the system from s2idle when pressing the power-button, let's
> > convert from using pm_wakeup_event() to pm_wakeup_dev_event(), as it allows
> > us to specify the "hard" in-parameter, which needs to be set for s2idle.
>
> I was looking at pm_wakeup_event() and pm_wakeup_dev_event() and I am
> afraid I do not understand the distinction. Why would we want to
> abort suspend by only by some wakeup sources and not by others? And why
> does a driver need to know whether a system uses s2idle or some other
> implementation of low power state?

Good question!

In regards to waking up. The CPU that wakes up from suspend-to-idle
may actually decide to just go back to idle, without doing a full
system resume - unless there is a wakeup that requires the system to
resume.

In suspend-to-ram a wakeup will always trigger a full system resume.

In most cases a driver doesn't really need to distinguish between
these cases, yet the wakeup APIs are designed to allow it. That's the
reason why pm_system_wakeup() needs to be called (controlled by "hard"
in-parameter to pm_wakeup_dev_event()).

>
> FWIW we have Chromebooks that use S0ix and Chromebooks that use S3 as
> well as ARM Chromebooks and I do not think they use
> pm_wakeup_dev_event() variant.
>
> I'm cc-ing Rafael to give us some guidance.

Good, let's see if there is something I failed to explain.

>
> >
> > Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
> > ---
> >  drivers/input/misc/hisi_powerkey.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/input/misc/hisi_powerkey.c b/drivers/input/misc/hisi_powerkey.c
> > index d3c293a95d32..d315017324d9 100644
> > --- a/drivers/input/misc/hisi_powerkey.c
> > +++ b/drivers/input/misc/hisi_powerkey.c
> > @@ -30,7 +30,7 @@ static irqreturn_t hi65xx_power_press_isr(int irq, void *q)
> >  {
> >       struct input_dev *input = q;
> >
> > -     pm_wakeup_event(input->dev.parent, MAX_HELD_TIME);
> > +     pm_wakeup_dev_event(input->dev.parent, MAX_HELD_TIME, true);
> >       input_report_key(input, KEY_POWER, 1);
> >       input_sync(input);
> >
> > --
> > 2.43.0
> >
>
> Thanks.
>
> --
> Dmitry

Kind regards
Uffe