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

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Date:	Tue, 18 Nov 2014 10:00:53 -0800
From:	Dmitry Torokhov <dtor@...omium.org>
To:	Dmitry Torokhov <dtor@...omium.org>
Cc:	"Rafael J. Wysocki" <rafael@...nel.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Benson Leung <bleung@...omium.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI: do not fail suspend if unable to configure wakeup

Hi Rafael,

On Thu, Oct 16, 2014 at 9:05 AM, Dmitry Torokhov <dtor@...omium.org> wrote:
> Hi Rafael,
>
> On Thu, Oct 16, 2014 at 10:10:20AM +0200, Rafael J. Wysocki wrote:
>> Hi,
>>
>> On Thu, Oct 16, 2014 at 12:56 AM, Dmitry Torokhov <dtor@...omium.org> wrote:
>> > Newer kernels put i2c devices with ACPI companion in ACPI power domain and
>> > then ACPI will try to configure them for wakeup (if requested).
>> > Unfortunately on some Chromebooks firmware separates wakeup GPIO into a
>> > completely separate device (which is handled by the kernel as a sleep
>> > button), leaving the touchpads themselves not wakeup capable (as far as
>> > ACPI is concerned). This causes ACPI late suspend code to fail to configure
>> > them as wakeup sources and aborts entire suspend.
>> >
>> > To work around this issues let's not abort entire suspend process if
>> > driver asked to be a wakeup source but ACPI can not satisfy that
>> > request.
>> >
>> > Note that originally I tried to simply change the driver to not mark
>> > device as wakeup source, unfortunately then we do not know that we
>> > should not be powering down the device completely, otherwise we can't
>> > wake up.
>> >
>> > Verified by making sure that "echo mem > /sys/power/state" works on
>> > Squawks.
>> >
>> > Reviewed-by: Benson Leung <bleung@...omium.org>
>> > Signed-off-by: Dmitry Torokhov <dtor@...omium.org>
>> > ---
>> >  drivers/acpi/device_pm.c | 16 ++++++++++++----
>> >  1 file changed, 12 insertions(+), 4 deletions(-)
>> >
>> > diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
>> > index 67075f8..440bc3d 100644
>> > --- a/drivers/acpi/device_pm.c
>> > +++ b/drivers/acpi/device_pm.c
>> > @@ -871,6 +871,7 @@ int acpi_dev_suspend_late(struct device *dev)
>> >         struct acpi_device *adev = ACPI_COMPANION(dev);
>> >         u32 target_state;
>> >         bool wakeup;
>> > +       bool can_wakeup;
>> >         int error;
>> >
>> >         if (!adev)
>> > @@ -878,12 +879,19 @@ int acpi_dev_suspend_late(struct device *dev)
>> >
>> >         target_state = acpi_target_system_state();
>> >         wakeup = device_may_wakeup(dev);
>> > -       error = acpi_device_wakeup(adev, target_state, wakeup);
>> > -       if (wakeup && error)
>> > -               return error;
>> > +       can_wakeup = acpi_device_can_wakeup(adev);
>> > +
>> > +       if (can_wakeup) {
>> > +               error = acpi_device_wakeup(adev, target_state, wakeup);
>> > +               if (wakeup && error)
>> > +                       return error;
>> > +       } else if (wakeup) {
>>
>> I think we just need to return an error code in that case, because otherwise
>
> We used to return error and that error aborted the suspend altogether,
> which prompted creating this patch.
>
>> this is potentially dangerous (worst case, it may be impossible to wake up
>> the machine at all after that).
>
> Yes, there is such potential, but that kind of error (no working wakeup
> sources) will be discovered before a box is shipped. Right now we have
> boxes in the wild that suspend fine with 3.10 and refuse to suspend with
> 3.14 because between 3.10 and 3.14 we started placing i2c devices with
> ACPI companions into ACPI power domain and ACPI power domain is now
> trying to configure them as wakeup sources and fails.

A gentle ping on the patch - without it (or something else) we basically
have a regression on shipped hardware: Chromebooks that were
suspending fine with 3.10 refuse to suspend with 3.14.

Thanks.

-- 
Dmitry
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