PM / PCI / ACPI: Kick devices that might have been reset by firmware
authorRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tue, 6 Oct 2015 22:50:24 +0000 (00:50 +0200)
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>
Wed, 14 Oct 2015 00:17:34 +0000 (02:17 +0200)
commit58a1fbbb2ee873dd1fe327e80bc7b08e80866269
tree3c3552e6631af82c4afb3f449ae8042bc925bf53
parentef25ba0476015908ef5960f9faac149ddf34ede0
PM / PCI / ACPI: Kick devices that might have been reset by firmware

There is a concern that if the platform firmware was involved in
the system resume that's being completed,  some devices might have
been reset by it and if those devices had the power.direct_complete
flag set during the preceding suspend transition, they may stay
in a reset-power-on state indefinitely (until they are runtime-resumed
and then suspended again).  That may not be a big deal from the
individual device's perspective, but if the system is an SoC, it may
be prevented from entering deep SoC-wide low-power states on idle
because of that.

The devices that are most likely to be affected by this issue are
PCI devices and ACPI-enumerated devices using the general ACPI PM
domain, so to prevent it from happening for those devices, force a
runtime resume for them if they have their power.direct_complete
flags set and the platform firmware was involved in the resume
transition currently in progress.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
drivers/acpi/acpi_lpss.c
drivers/acpi/device_pm.c
drivers/base/power/generic_ops.c
drivers/pci/pci-driver.c
include/linux/pm.h