tree df430581d3246509ae1e84cc994309002c796d76
parent 709f94ff018a4403d0bb32643254058d5d9cfa24
author Rafael J. Wysocki <rafael.j.wysocki@intel.com> 1483061251 +0100
committer Rafael J. Wysocki <rafael.j.wysocki@intel.com> 1483392119 +0100

ACPI / scan: Prefer devices without _HID/_CID for _ADR matching

The way acpi_find_child_device() works currently is that, if there
are two (or more) devices with the same _ADR value in the same
namespace scope (which is not specifically allowed by the spec and
the OS behavior in that case is not defined), the first one of them
found to be present (with the help of _STA) will be returned.

This covers the majority of cases, but is not sufficient if some of
the devices in question have a _HID (or _CID) returning some valid
ACPI/PNP device IDs (which is disallowed by the spec) and the
ASL writers' expectation appears to be that the OS will match
devices without a valid ACPI/PNP device ID against a given bus
address first.

To cover this special case as well, modify find_child_checks()
to prefer devices without ACPI/PNP device IDs over devices that
have them.

Suggested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>