[PATCH 6/13] ACPI / PM: Introduce __acpi_bus_get_power()

Rafael J. Wysocki
2010-11-24T23:07:56Z

It sometimes is necessary to get the power state of an ACPI device
without updating its device->power.state field, for example to
avoid inconsistencies between device->power.state and the reference
counters of the device's power resources. For this purpose introduce
__acpi_bus_get_power() that will return the given device's power
state via a pointer (instead of modifying device->power.state)
and make acpi_bus_get_power() use it.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/acpi/bus.c | 48 +++++++++++++++++++++++++++++-------------------
1 file changed, 29 insertions(+), 19 deletions(-)

Index: linux-2.6/drivers/acpi/bus.c
===================================================================
--- linux-2.6.orig/drivers/acpi/bus.c
+++ linux-2.6/drivers/acpi/bus.c
@@ -196,34 +196,24 @@ EXPORT_SYMBOL(acpi_bus_get_private_data)
Power Management
-------------------------------------------------------------------------- */

-int acpi_bus_get_power(acpi_handle handle, int *state)
+static int __acpi_bus_get_power(struct acpi_device *device, int *state)
{
int result = 0;
acpi_status status = 0;
- struct acpi_device *device = NULL;
unsigned long long psc = 0;

-
- result = acpi_bus_get_device(handle, &device);
- if (result)
- return result;
+ if (!device || !state)
+ return -EINVAL;

*state = ACPI_STATE_UNKNOWN;

- if (!device->flags.power_manageable) {
- /* TBD: Non-recursive algorithm for walking up hierarchy */
- if (device->parent)
- *state = device->parent->power.state;
- else
- *state = ACPI_STATE_D0;
- } else {
+ if (device->flags.power_manageable) {
/*
* Get the device's power state either directly (via _PSC) or
* indirectly (via power resources).
*/
if (device->power.flags.power_resources) {
- result = acpi_power_get_inferred_state(device,
- &device->power.state);
+ result = acpi_power_get_inferred_state(device, state);
if (result)
return result;
} else if (device->power.flags.explicit_get) {
@@ -231,20 +221,40 @@ int acpi_bus_get_power(acpi_handle handl
NULL, &psc);
if (ACPI_FAILURE(status))
return -ENODEV;
- device->power.state = (int)psc;
+ *state = (int)psc;
}
-
- *state = device->power.state;
+ } else {
+ /* TBD: Non-recursive algorithm for walking up hierarchy. */
+ *state = device->parent ?
+ device->parent->power.state : ACPI_STATE_D0;
}

ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] power state is D%d\n",
- device->pnp.bus_id, device->power.state));
+ device->pnp.bus_id, *state));

return 0;
}

+
+int acpi_bus_get_power(acpi_handle handle, int *state)
+{
+ struct acpi_device *device;
+ int result;
+
+ result = acpi_bus_get_device(handle, &device);
+ if (result)
+ return result;
+
+ result = __acpi_bus_get_power(device, state);
+ if (result)
+ return result;
+
+ device->power.state = *state;
+ return 0;
+}
EXPORT_SYMBOL(acpi_bus_get_power);

+
int acpi_bus_set_power(acpi_handle handle, int state)
{
int result = 0;