In some cases ACPI control methods used during device enumeration
(such as _HID or _STA) may rely on Operation Region handlers
supplied by the drivers of other devices [1]:
An example of this is the Acer Switch 10E SW3-016 model. The _HID
method of the ACPI node for the UART attached Bluetooth, reads
GPIOs to detect the installed wifi chip and update the _HID for the
Bluetooth's ACPI node accordingly. The current ACPI scan code calls
_HID before the GPIO controller's OpRegions are available, leading
to the wrong _HID being used and Bluetooth not working.
In principle, in those cases there should be a _DEP control method
under the device object with OpRegion enumeration dependencies, so
deferring the enumeration of devices with _DEP returning a non-empty
list of suppliers of OpRegions depended on by the given device
(modulo some known exceptions that don't really supply any OpRegions
and are listed by _DEP for other reasons irrelevant for Linux) should
at least address the first-order dependencies by allowing the OpRegion
suppliers to be enumerated before their consumers.
Implement the above idea by modifying acpi_bus_scan() to enumerate
devices in the given scope of the ACPI namespace in two passes,
where the first pass covers the devices without "significant" lists
of dependencies coming from _DEP only and the second pass covers
all of the devices that were not enumerated in the first pass.
Take _DEP into account only for device objects with _HID, mostly in
order to avoid deferring the creation of ACPI device objects that
represent PCI devices and must be present during the enumeration
of the PCI bus (which takes place during the processing of the ACPI
device object that represents the host bridge), so that they can
be properly associated with the corresponding PCI devices.
Link: https://lore.kernel.org/linux-acpi/20201121203040.146252-1-hdegoede@redhat.com/ # [1]
Reported-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
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