Two power buttons recognized: PWRF and PWRB

Paul Menzel <paulepanter@xxxxxxxxxxxxxxxxxxxxx> · Mon, 23 Jul 2012 10:32:07 +0200

Dear Linux folks,

due to another problem [1] I noticed that X recognizes two power
buttons.

        $ xinput
        ⎡ Virtual core pointer                    	id=2	[master pointer  (3)]
        ⎜   ↳ Virtual core XTEST pointer              	id=4	[slave  pointer  (2)]
        ⎜   ↳ HID 1241:1122                           	id=8	[slave  pointer  (2)]
        ⎣ Virtual core keyboard                   	id=3	[master keyboard (2)]
            ↳ Virtual core XTEST keyboard             	id=5	[slave  keyboard (3)]
            ↳ Power Button                            	id=6	[slave  keyboard (3)]
            ↳ Power Button                            	id=7	[slave  keyboard (3)]
            ↳ Logitech Logitech USB Keyboard          	id=9	[slave  keyboard (3)]
            ↳ Logitech Logitech USB Keyboard          	id=10	[slave  keyboard (3)]

This is due to Linux setting up two of these buttons.

        $ dmesg | grep -i "power button"
        [   16.785490] input: Power Button as /devices/LNXSYSTM:00/device:00/PNP0C0C:00/input/input3
        [   16.785496] ACPI: Power Button [PWRB]
        [   16.785696] input: Power Button as /devices/LNXSYSTM:00/LNXPWRBN:00/input/input4
        [   16.785699] ACPI: Power Button [PWRF]

I am not sure if this is an input or ACPI problem and if it is a problem
at all. Pressing the power button does generate the correct events – I
think. At least the system shuts down or suspends just fine. It just
seems weird that two of these buttons are set up.

This seems to be a common “problem” as this happens with for example
ASUS M2A-VM [2] and ASRock A780FullHD.

Searching the WWW I did not find a lot of information. Just an article
in the Gentoo Wiki suggesting that only one button should be recognized
[3]. Though I emphasize again that the power button works fine!

Thanks,

Paul

[1] https://bugs.freedesktop.org/show_bug.cgi?id=52046#c5
[2] https://bugzilla.kernel.org/show_bug.cgi?id=42587#c11
[3] http://en.gentoo-wiki.com/wiki/ACPI/Fix_common_problems#Power_and.2For_Sleep_Buttons_Don.27t_Work