tree 794af5380ef5c6a47f4f0e6bba50b6dfea448267
parent ecde3003e5205a283b46b931c729a2aecab64ba1
author Jeff Wu <zlinuxkernel@gmail.com> 1369809090 +0000
committer Rafael J. Wysocki <rafael.j.wysocki@intel.com> 1371677698 +0200

ACPI: add _STA evaluation at do_acpi_find_child()

Once do_acpi_find_child() has found the first matching handle, it
makes the acpi_get_child() loop stop and return that handle.  On some
platforms, though, there are multiple devices with the same value of
"_ADR" in the same namespace scope, and if one of them is enabled,
the others will be disabled.  For example:

 Address : 0x1FFFF ; path : SB_PCI0.SATA.DEV0
 Address : 0x1FFFF ; path : SB_PCI0.SATA.DEV1
 Address : 0x1FFFF ; path : SB_PCI0.SATA.DEV2

If DEV0 and DEV1 are disabled and DEV2 is enabled, the handle of DEV2
should be returned, but actually the function always returns the
handle of DEV0.

To address that issue, make do_acpi_find_child() evaluate _STA to
check the device status.  If a matching device object exists, but is
disabled, acpi_get_child() will continue to walk the namespace in the
hope of finding an enabled one.  If one is found, its handle will be
returned, but otherwise the function will return the handle of the
disabled object found before (in case it is enabled going forward).

[rjw: Changelog]
Signed-off-by: Jeff Wu <zlinuxkernel@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>