[PATCH] ACPI / scan: Treat power resources in a special way

Rafael J. Wysocki
2012-12-31T00:41:07Z

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Commit 1d57433 (ACPI: Separate adding ACPI device objects from
probing ACPI drivers) introduced an ACPI power resources management
regression, because it didn't ensure that the power resources
driver bind to the struct acpi_device objects corresponding
to power resources as soon as they were created. As a result,
ACPI power management routines may attempt to access power resource
objects before they are ready to use.

To fix this problem, tell the acpi_add_single_object() in
acpi_bus_check_add() to probe the driver for objects of type
ACPI_BUS_TYPE_POWER. This fix has been verified to work on
HP nx6325 where the problem was first observed.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

The commit mentioned in the changelog is in linux-next only for now, but
it's likely to go upstream in this form anyway and the fix on top of the
whole ACPI scan series is trivial.

Thanks,
Rafael

---
drivers/acpi/scan.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux/drivers/acpi/scan.c
===================================================================
--- linux.orig/drivers/acpi/scan.c
+++ linux/drivers/acpi/scan.c
@@ -1606,7 +1606,8 @@ static acpi_status acpi_bus_check_add(ac
return AE_CTRL_DEPTH;
}

- acpi_add_single_object(&device, handle, type, sta, false);
+ acpi_add_single_object(&device, handle, type, sta,
+ type == ACPI_BUS_TYPE_POWER);
if (!device)
return AE_CTRL_DEPTH;