tree 5155c29dcc2abb3b8e1e3a395908ecb5906ffbe8
parent 31ade3b83e1821da5fbb2f11b5b3d4ab2ec39db8
author Aaron Lu <aaron.lu@intel.com> 1447902325 +0800
committer Rafael J. Wysocki <rafael.j.wysocki@intel.com> 1448892376 +0100

ACPI / scan: set status to 0 if _STA failed

Some ACPI node's _STA will touch operation region field, since the
evaluation of _STA in acpi_bus_type_and_status is very early, the
operation region handler is not ready yet. Instead of fail that function
and not creating the acpi_device node consequently, set status to 0 so
that later when the driver for that device is probing, it can find
the acpi_device node and proceed normally. And at that time, the
handler for the operation region is ready and its _STA evaluation will
succeed, its present status can be checked there.

Even there will be no driver using this node later, it doesn't seem
hurt to have one more acpi_device node created with status set to 0.

This happens on Microsoft Surface 3, where the SPI device node NTRG's
_STA touches GPIO fields and the SPI core driver will only enumerate SPI
devices from ACPI if the acpi_device node is 1: created; 2: _STA
indicates it's present.

Note that due to another problem in SPI driver, for NTRG to be actually
enumerated, some changes have to be made in the SPI layer, which is
addressed by Mika(not send out yet):
https://bugzilla.kernel.org/show_bug.cgi?id=104291#c23

Link: https://bugzilla.kernel.org/show_bug.cgi?id=104291
Reported-by: Bastien Nocera <bugzilla@hadess.net>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>