Message-ID: <cbbf0caf-82ce-4427-9844-b11e0f5cacdb@kernel.org>
Date: Thu, 26 Jun 2025 13:20:54 -0500
From: Mario Limonciello <superm1@...nel.org>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
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 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.

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);
+                       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]

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