[PATCH 10/13] ACPI / PM: Register power resource devices as soon as they are needed

Rafael J. Wysocki
2010-11-24T23:10:44Z

Depending on the organization of the ACPI namespace, power resource
device objects may generally be scanned after the "regular" device
objects that they are referred from through _PRn. This, in turn, may
cause acpi_bus_get_power_flags() to attempt to access them through
acpi_bus_init_power() before they are registered (and initialized by
acpi_power_driver). [This is not a theoretical issue, it actually
happens for one PnP device on my testbed HP nx6325.]

To fix this problem, make acpi_bus_get_power_flags() attempt to
register power resource devices as soon as they have been found in
the _PRn output for any other devices.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/acpi/scan.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

Index: linux-2.6/drivers/acpi/scan.c
===================================================================
--- linux-2.6.orig/drivers/acpi/scan.c
+++ linux-2.6/drivers/acpi/scan.c
@@ -827,6 +827,8 @@ end:
return 0;
}

+static void acpi_bus_add_power_resource(acpi_handle handle);
+
static int acpi_bus_get_power_flags(struct acpi_device *device)
{
acpi_status status = 0;
@@ -855,8 +857,12 @@ static int acpi_bus_get_power_flags(stru
acpi_evaluate_reference(device->handle, object_name, NULL,
&ps->resources);
if (ps->resources.count) {
+ int j;
+
device->power.flags.power_resources = 1;
ps->flags.valid = 1;
+ for (j = 0; j < ps->resources.count; j++)
+ acpi_bus_add_power_resource(ps->resources.handles[j]);
}

/* Evaluate "_PSx" to see if we can do explicit sets */
@@ -1303,6 +1309,20 @@ end:
#define ACPI_STA_DEFAULT (ACPI_STA_DEVICE_PRESENT | ACPI_STA_DEVICE_ENABLED | \
ACPI_STA_DEVICE_UI | ACPI_STA_DEVICE_FUNCTIONING)

+static void acpi_bus_add_power_resource(acpi_handle handle)
+{
+ struct acpi_bus_ops ops = {
+ .acpi_op_add = 1,
+ .acpi_op_start = 1,
+ };
+ struct acpi_device *device = NULL;
+
+ acpi_bus_get_device(handle, &device);
+ if (!device)
+ acpi_add_single_object(&device, handle, ACPI_BUS_TYPE_POWER,
+ ACPI_STA_DEFAULT, &ops);
+}
+
static int acpi_bus_type_and_status(acpi_handle handle, int *type,
unsigned long long *sta)
{