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Message-ID: <tpetaw6qdwojt46fcmzlmy2hdegbuwcjnbah7uebj6ilegfk4y@5uo6a7ediaw2>
Date: Thu, 26 Jun 2025 12:06:11 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Mario Limonciello <superm1@...nel.org>
Cc: Hans de Goede <hansg@...nel.org>, Mika Westerberg <westeri@...nel.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Linus Walleij <linus.walleij@...aro.org>,
Bartosz Golaszewski <brgl@...ev.pl>, "open list:GPIO ACPI SUPPORT" <linux-gpio@...r.kernel.org>,
"open list:GPIO ACPI SUPPORT" <linux-acpi@...r.kernel.org>, open list <linux-kernel@...r.kernel.org>,
"open list:INPUT (KEYBOARD, MOUSE, JOYSTICK, TOUCHSCREEN)..." <linux-input@...r.kernel.org>, Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH v3 4/4] Input: Don't send fake button presses to wake
system
On Thu, Jun 26, 2025 at 01:55:29PM -0500, Mario Limonciello wrote:
> On 6/26/2025 1:48 PM, Dmitry Torokhov wrote:
> > On Thu, Jun 26, 2025 at 01:20:54PM -0500, Mario Limonciello wrote:
> > > On 6/26/2025 1:07 PM, Dmitry Torokhov wrote:
> > > > On Thu, Jun 26, 2025 at 12:53:02PM -0500, Mario Limonciello wrote:
> > > > >
> > > > >
> > > > > On 6/26/25 12:44 PM, Dmitry Torokhov wrote:
> > > > > > Hi Mario,
> > > > > >
> > > > > > On Thu, Jun 26, 2025 at 06:33:08AM -0500, Mario Limonciello wrote:
> > > > > > >
> > > > > > >
> > > > > > > On 6/26/25 3:35 AM, Hans de Goede wrote:
> > > > > > > > Hi Mario,
> > > > > > > >
> > > > > > > > On 25-Jun-25 23:58, Mario Limonciello wrote:
> > > > > > > > > From: Mario Limonciello <mario.limonciello@....com>
> > > > > > > > >
> > > > > > > > > Sending an input event to wake a system does wake it, but userspace picks
> > > > > > > > > up the keypress and processes it. This isn't the intended behavior as it
> > > > > > > > > causes a suspended system to wake up and then potentially turn off if
> > > > > > > > > userspace is configured to turn off on power button presses.
> > > > > > > > >
> > > > > > > > > Instead send a PM wakeup event for the PM core to handle waking the system.
> > > > > > > > >
> > > > > > > > > Cc: Hans de Goede <hansg@...nel.org>
> > > > > > > > > Fixes: 0f107573da417 ("Input: gpio_keys - handle the missing key press event in resume phase")
> > > > > > > > > Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> > > > > > > > > ---
> > > > > > > > > drivers/input/keyboard/gpio_keys.c | 7 +------
> > > > > > > > > 1 file changed, 1 insertion(+), 6 deletions(-)
> > > > > > > > >
> > > > > > > > > diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
> > > > > > > > > index 773aa5294d269..4c6876b099c43 100644
> > > > > > > > > --- a/drivers/input/keyboard/gpio_keys.c
> > > > > > > > > +++ b/drivers/input/keyboard/gpio_keys.c
> > > > > > > > > @@ -420,12 +420,7 @@ static irqreturn_t gpio_keys_gpio_isr(int irq, void *dev_id)
> > > > > > > > > pm_stay_awake(bdata->input->dev.parent);
> > > > > > > > > if (bdata->suspended &&
> > > > > > > > > (button->type == 0 || button->type == EV_KEY)) {
> > > > > > > > > - /*
> > > > > > > > > - * Simulate wakeup key press in case the key has
> > > > > > > > > - * already released by the time we got interrupt
> > > > > > > > > - * handler to run.
> > > > > > > > > - */
> > > > > > > > > - input_report_key(bdata->input, button->code, 1);
> > > > > > > > > + pm_wakeup_event(bdata->input->dev.parent, 0);
> > > > > >
> > > > > > There is already pm_stay_awake() above.
> > > > >
> > > > > But that doesn't help with the fact that userspace gets KEY_POWER from this
> > > > > and reacts to it.
> > > > >
> > > > > >
> > > > > > > > > }
> > > > > > > > > }
> > > > > > > >
> > > > > > > > Hmm, we have the same problem on many Bay Trail / Cherry Trail
> > > > > > > > windows 8 / win10 tablets, so this has been discussed before and e.g.
> > > > > > > > Android userspace actually needs the button-press (evdev) event to not
> > > > > > > > immediately go back to sleep, so a similar patch has been nacked in
> > > > > > > > the past.
> > > > > > > >
> > > > > > > > At least for GNOME this has been fixed in userspace by ignoring
> > > > > > > > power-button events the first few seconds after a resume from suspend.
> > > > > > > >
> > > > > > >
> > > > > > > The default behavior for logind is:
> > > > > > >
> > > > > > > HandlePowerKey=poweroff
> > > > > > >
> > > > > > > Can you share more about what version of GNOME has a workaround?
> > > > > > > This was actually GNOME (on Ubuntu 24.04) that I found this issue.
> > > > > > >
> > > > > > > Nonetheless if this is dependent on an Android userspace problem could we
> > > > > > > perhaps conditionalize it on CONFIG_ANDROID_BINDER_DEVICES?
> > > > > >
> > > > > > No it is not only Android, other userspace may want to distinguish
> > > > > > between normal and "dark" resume based on keyboard or other user
> > > > > > activity.
> > > > > >
> > > > > > Thanks.
> > > > > >
> > > > > In this specific case does the key passed up to satisfy this userspace
> > > > > requirement and keep it awake need to specifically be a fabricated
> > > > > KEY_POWER?
> > > > >
> > > > > Or could we find a key that doesn't require some userspace to ignore
> > > > > KEY_POWER?
> > > > >
> > > > > Maybe something like KEY_RESERVED, KEY_FN, or KEY_POWER2?
> > > >
> > > > The code makes no distinction between KEY_POWER and KEY_A or KEY_B, etc.
> > > > It simply passes event to userspace for processing.
> > >
> > > Right. I don't expect a problem with most keys, but my proposal is to
> > > special case KEY_POWER while suspended. If a key press event must be sent
> > > to keep Android and other userspace happy I suggest sending something
> > > different just for that situation.
> >
> > I do not know if userspace specifically looks for KEY_POWER or if it
> > looks for user input in general, and I'd rather be on safe side and not
> > mangle user input.
> >
> > As Hans mentioned, at least some userspace already prepared to deal with
> > this issue. And again, this only works if by the time ISR/debounce
> > runs the key is already released. What if it is still pressed? You still
> > going to observe KEY_POWER and need to suppress turning off the screen.
> >
> > >
> > > Like this:
> > >
> > > diff --git a/drivers/input/keyboard/gpio_keys.c
> > > b/drivers/input/keyboard/gpio_keys.c
> > > index 773aa5294d269..66e788d381956 100644
> > > --- a/drivers/input/keyboard/gpio_keys.c
> > > +++ b/drivers/input/keyboard/gpio_keys.c
> > > @@ -425,7 +425,10 @@ static irqreturn_t gpio_keys_gpio_isr(int irq, void
> > > *dev_id)
> > > * already released by the time we got interrupt
> > > * handler to run.
> > > */
> > > - input_report_key(bdata->input, button->code, 1);
> > > + if (button->code == KEY_POWER)
> > > + input_report_key(bdata->input, KEY_WAKEUP,
> > > 1);
> >
> > Just FYI: Here your KEY_WAKEUP is stuck forever.
>
> Thanks.
>
> >
> > > + else
> > > + input_report_key(bdata->input, button->code,
> > > 1);
> > > }
> > > }
> > >
> > >
> > >
> > > >
> > > > You need to fix your userspace. Even with your tweak it is possible for
> > > > userspace to get a normal key event "too early" and turn off the screen
> > > > again, so you still need to handle this situation.
> > > >
> > > > Thanks.
> > > >
> > >
> > > I want to note this driver works quite differently than how ACPI power
> > > button does.
> > >
_> > > You can see in acpi_button_notify() that the "keypress" is only forwarded
> > > when not suspended [1]. Otherwise it's just wakeup event (which is what my
> > > patch was modeling).
> > >
> > > https://github.com/torvalds/linux/blob/v6.16-rc3/drivers/acpi/button.c#L461
> > > [1]
> >
> > If you check acpi_button_resume() you will see that the events are sent
> > from there. Except that for some reason they chose to use KEY_WAKEUP and
> > not KEY_POWER, oh well. Unlike acpi button driver gpio_keys is used on
> > multiple other platforms.
> >
> > Thanks.
> >
>
> Well that would explain the difference, and git blame gives the history [1].
>
> It's from enablement for Android with ACPI power button. That commit also
> mentions that Android can handle both POWER and WAKEUP from input device to
> wakeup the system. Non-Android userspace doesn't do anything with
> KEY_WAKEUP today.
*All* non-Android userspace?
>
> So this has me thinking the proposal I had above to special case KEY_POWER
> and translate to KEY_WAKEUP is the right way forward, just making sure to
> release the key as you rightfully pointed out.
You keep ignoring the fact that it does not solve your issue when the
key/button is pressed just a tad longer.
There are a ton of drivers that report KEY_POWER and do not convert it
to anything else on resume. I will not accept patches that mangle input
events in the gpio_keys driver, sorry.
Thanks.
--
Dmitry
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