[PATCH 3.17 070/122] ACPI / PM: Ignore wakeup setting if the ACPI companion cant wake up

From: Greg Kroah-Hartman
Date: Fri Dec 05 2014 - 18:39:05 EST

3.17-stable review patch. If anyone has any objections, please let me know.


From: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>

commit 78579b7c7eb45f0e7ec5e9437087ed21749f9a9c upstream.

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 and
the ACPI PM layer has no information on the wakeup capability. As
a result, device_may_wakeup(dev) called from acpi_dev_suspend_late()
returns 'true' for those devices, but the wakeup.flags.valid flag is
unset for the corresponding ACPI device objects, so acpi_device_wakeup()
reproducibly fails for them causing acpi_dev_suspend_late() to return
an error code. The entire system suspend is then aborted and the
machines in question cannot suspend 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
being handled has wakeup.flags.valid unset (in which case it is clear
that the wakeup is supposed to be handled by other means).

This fixes a regression introduced by commit a76e9bd89ae7 (i2c:
attach/detach I2C client device to the ACPI power domain) as the
affected systems could suspend and resume successfully before that

Fixes: a76e9bd89ae7 (i2c: attach/detach I2C client device to the ACPI power domain)
Reported-by: Dmitry Torokhov <dtor@xxxxxxxxxxxx>
Reviewed-by: Dmitry Torokhov <dtor@xxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/acpi/device_pm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -877,7 +877,7 @@ 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;

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/