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Message-ID: <vkau25ybcx3bcoa2jmxlukumunzii5h6em43anh6mmzk2kyiv7@kyych4kxc4zo>
Date: Thu, 26 Jun 2025 12:14:22 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Hans de Goede <hansg@...nel.org>
Cc: Mario Limonciello <superm1@...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 08:57:30PM +0200, Hans de Goede wrote:
> Hi,
>
> On 26-Jun-25 20:48, 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.
> >
> >> + 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.
>
> Interesting, but the ACPI button code presumably only does this on resume
> for a normal press while the system is awake it does use KEY_POWER, right ?
Yes. It is unclear to me why they chose to mangle the event on wakeup,
it does not seem to be captured in the email discussions or in the patch
description.
Thanks.
--
Dmitry
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