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Subject[PATCH 8/13] ACPI / PM: Add function for updating device power state consistently
Date
From: Rafael J. Wysocki <rjw@sisk.pl>

Add function acpi_bus_update_power() for reading the actual power
state of an ACPI device and updating its device->power.state field
in such a way that its power resources' reference counters will
remain consistent with that field.

For this purpose introduce __acpi_bus_set_power() setting the
power state of an ACPI device without updating its
device->power.state field and make acpi_bus_set_power() and
acpi_bus_update_power() use it (acpi_bus_set_power() retains the
current behavior for now).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/acpi/bus.c | 90 ++++++++++++++++++++++++++++++++----------------
include/acpi/acpi_bus.h | 1
2 files changed, 62 insertions(+), 29 deletions(-)
Index: linux-2.6/drivers/acpi/bus.c
===================================================================
--- linux-2.6.orig/drivers/acpi/bus.c
+++ linux-2.6/drivers/acpi/bus.c
@@ -255,44 +255,17 @@ int acpi_bus_get_power(acpi_handle handl
EXPORT_SYMBOL(acpi_bus_get_power);


-int acpi_bus_set_power(acpi_handle handle, int state)
+static int __acpi_bus_set_power(struct acpi_device *device, int state)
{
int result = 0;
acpi_status status = AE_OK;
- struct acpi_device *device = NULL;
char object_name[5] = { '_', 'P', 'S', '0' + state, '\0' };

-
- result = acpi_bus_get_device(handle, &device);
- if (result)
- return result;
-
- if ((state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
+ if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
return -EINVAL;

/* Make sure this is a valid target state */

- if (!device->flags.power_manageable) {
- ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device `[%s]' is not power manageable\n",
- kobject_name(&device->dev.kobj)));
- return -ENODEV;
- }
- /*
- * Get device's current power state
- */
- if (!acpi_power_nocheck) {
- /*
- * Maybe the incorrect power state is returned on the bogus
- * bios, which is different with the real power state.
- * For example: the bios returns D0 state and the real power
- * state is D3. OS expects to set the device to D0 state. In
- * such case if OS uses the power state returned by the BIOS,
- * the device can't be transisted to the correct power state.
- * So if the acpi_power_nocheck is set, it is unnecessary to
- * get the power state by calling acpi_bus_get_power.
- */
- acpi_bus_get_power(device->handle, &device->power.state);
- }
if ((state == device->power.state) && !device->flags.force_power_state) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device is already at D%d\n",
state));
@@ -362,6 +335,42 @@ int acpi_bus_set_power(acpi_handle handl
return result;
}

+
+int acpi_bus_set_power(acpi_handle handle, int state)
+{
+ struct acpi_device *device;
+ int result;
+
+ result = acpi_bus_get_device(handle, &device);
+ if (result)
+ return result;
+
+ if (!device->flags.power_manageable) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "Device [%s] is not power manageable\n",
+ dev_name(&device->dev)));
+ return -ENODEV;
+ }
+
+ /*
+ * Get device's current power state
+ */
+ if (!acpi_power_nocheck) {
+ /*
+ * Maybe the incorrect power state is returned on the bogus
+ * bios, which is different with the real power state.
+ * For example: the bios returns D0 state and the real power
+ * state is D3. OS expects to set the device to D0 state. In
+ * such case if OS uses the power state returned by the BIOS,
+ * the device can't be transisted to the correct power state.
+ * So if the acpi_power_nocheck is set, it is unnecessary to
+ * get the power state by calling acpi_bus_get_power.
+ */
+ __acpi_bus_get_power(device, &device->power.state);
+ }
+
+ return __acpi_bus_set_power(device, state);
+}
EXPORT_SYMBOL(acpi_bus_set_power);


@@ -389,6 +398,29 @@ int acpi_bus_init_power(struct acpi_devi
}


+int acpi_bus_update_power(acpi_handle handle, int *state_p)
+{
+ struct acpi_device *device;
+ int state;
+ int result;
+
+ result = acpi_bus_get_device(handle, &device);
+ if (result)
+ return result;
+
+ result = __acpi_bus_get_power(device, &state);
+ if (result)
+ return result;
+
+ result = __acpi_bus_set_power(device, state);
+ if (!result && state_p)
+ *state_p = state;
+
+ return result;
+}
+EXPORT_SYMBOL_GPL(acpi_bus_update_power);
+
+
bool acpi_bus_power_manageable(acpi_handle handle)
{
struct acpi_device *device;
Index: linux-2.6/include/acpi/acpi_bus.h
===================================================================
--- linux-2.6.orig/include/acpi/acpi_bus.h
+++ linux-2.6/include/acpi/acpi_bus.h
@@ -330,6 +330,7 @@ acpi_status acpi_bus_get_status_handle(a
int acpi_bus_get_status(struct acpi_device *device);
int acpi_bus_get_power(acpi_handle handle, int *state);
int acpi_bus_set_power(acpi_handle handle, int state);
+int acpi_bus_update_power(acpi_handle handle, int *state_p);
bool acpi_bus_power_manageable(acpi_handle handle);
bool acpi_bus_can_wakeup(acpi_handle handle);
#ifdef CONFIG_ACPI_PROC_EVENT


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