Re: [PATCH] ACPI / scan: Prefer devices without _HID/_CID for _ADR matching

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Fri, Dec 30, 2016 at 02:27:31AM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> 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>

Thanks for taking care of this Rafael :)