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    SubjectRe: [REGRESSION 4.17] Spurious wakeup / reboot with power button
    On Thu, 05 Jul 2018 11:34:59 +0200,
    Rafael J. Wysocki wrote:
    >
    > Hi,
    >
    > On Thu, Jul 5, 2018 at 9:05 AM, Takashi Iwai <tiwai@suse.de> wrote:
    > > Hi,
    > >
    > > we've got a regression report since 4.17 about the behavior of
    > > power-off with the power button. When a machine is powered off with
    > > the power button on desktop, it reboots after a few seconds instead of
    > > power down.
    > >
    > > The manual power down via "systemctl poweroff" works fine, so it's
    > > possibly some spurious wakeup by the power button action, and some
    > > ACPI-related change is suspected.
    > > The regression still remains in 4.18-rc3.
    >
    > There are only a few ACPI commits directly related to power management
    > between 4.16 and 4.17 and none of them looks particularly suspicious.

    OK, interesting.

    > It looks like the power button state may not be cleared sufficiently
    > after it's been pressed which is now visible for some reason.

    Hmm, where can such a state remain? Since it happens after the
    machine turned off, some (ACPI) wakeup bits?

    > How does the button poweroff work, exactly? I guess the event is
    > collected by a user space demon which then triggers power of via sysfs
    > or similar?

    Usually X desktop environment receives an input event from the ACPI
    power button input device, and deals the event accordingly depending
    on the setup. The power-down behavior itself should be equivalent
    with "systemctl poweroff" or such.


    thanks,

    Takashi

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