Re: [PATCH] ACPI: do not fail suspend if unable to configure wakeup

From: Dmitry Torokhov
Date: Tue Nov 18 2014 - 19:14:55 EST

On Tue, Nov 18, 2014 at 4:20 PM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> It goes again below with a changelog, but since technically it is a regression
> fix, I'd like to push it for "stable" too. I suppose that the commit that
> things stopped working after is a76e9bd89ae7 (i2c: attach/detach I2C client
> device to the ACPI power domain). Is that correct?


> Rafael
> --
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Subject: ACPI / PM: Ignore wakeup setting if the ACPI companion can't wake up
> As reported by Dmitry, on some Chromebooks there are devices with
> corresponding ACPI objects and with unusual system wakeup
> configuration. Namely, they technically are wakeup-capable, but the
> wakeup is handled via a platform-specific out-of-band mechanism
> rather than by standard ACPI means.

I think they are using standard ACPI wakeup methods, but in a very perverted
way: there is "shadow" ACPI sleep button corresponding to the GPIO assigned
to the trackpad or touchscreen; it is just not tied to touchpad/touchscreen
device in DSDT.

We won't have such set up again, but we do have existing boxes that are
like that.

> As a result, the
> device_may_wakeup(dev) called from acpi_dev_suspend_late() returns
> 'true' for them, but the wakeup.flags.valid flag is unset for the
> corresponding ACPI device objects, so acpi_dev_suspend_late()
> reproducibly returns an error for them causing the entire system
> suspend to be aborted. Consequently, system suspend doesn't work
> on those machines at all.
> Address the problem by ignoring the device_may_wakeup(dev) return
> value in acpi_dev_suspend_late() if the ACPI companion of the device
> in question has wakeup.flags.valid unset (in which case it is clear
> that the wakeup cannot happen via ACPI).
> Reported-by: Dmitry Torokhov <dtor@xxxxxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> drivers/acpi/device_pm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> Index: linux-pm/drivers/acpi/device_pm.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/device_pm.c
> +++ linux-pm/drivers/acpi/device_pm.c
> @@ -878,7 +878,7 @@ int acpi_dev_suspend_late(struct device
> return 0;
> target_state = acpi_target_system_state();
> - wakeup = device_may_wakeup(dev);
> + wakeup = device_may_wakeup(dev) && acpi_device_can_wakeup(adev);
> error = acpi_device_wakeup(adev, target_state, wakeup);
> if (wakeup && error)
> return error;
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