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path: root/drivers/acpi/device_pm.c
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Diffstat (limited to 'drivers/acpi/device_pm.c')
-rw-r--r--drivers/acpi/device_pm.c53
1 files changed, 45 insertions, 8 deletions
diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index 3269a4e8b902..94194c7e8a07 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -53,6 +53,19 @@ const char *acpi_power_state_string(int state)
}
}
+static int acpi_dev_pm_explicit_get(struct acpi_device *device, int *state)
+{
+ unsigned long long psc;
+ acpi_status status;
+
+ status = acpi_evaluate_integer(device->handle, "_PSC", NULL, &psc);
+ if (ACPI_FAILURE(status))
+ return -ENODEV;
+
+ *state = psc;
+ return 0;
+}
+
/**
* acpi_device_get_power - Get power state of an ACPI device.
* @device: Device to get the power state of.
@@ -65,6 +78,7 @@ const char *acpi_power_state_string(int state)
int acpi_device_get_power(struct acpi_device *device, int *state)
{
int result = ACPI_STATE_UNKNOWN;
+ int error;
if (!device || !state)
return -EINVAL;
@@ -81,18 +95,16 @@ int acpi_device_get_power(struct acpi_device *device, int *state)
* if available.
*/
if (device->power.flags.power_resources) {
- int error = acpi_power_get_inferred_state(device, &result);
+ error = acpi_power_get_inferred_state(device, &result);
if (error)
return error;
}
if (device->power.flags.explicit_get) {
- acpi_handle handle = device->handle;
- unsigned long long psc;
- acpi_status status;
+ int psc;
- status = acpi_evaluate_integer(handle, "_PSC", NULL, &psc);
- if (ACPI_FAILURE(status))
- return -ENODEV;
+ error = acpi_dev_pm_explicit_get(device, &psc);
+ if (error)
+ return error;
/*
* The power resources settings may indicate a power state
@@ -160,7 +172,8 @@ int acpi_device_set_power(struct acpi_device *device, int state)
/* Make sure this is a valid target state */
- if (state == device->power.state) {
+ /* There is a special case for D0 addressed below. */
+ if (state > ACPI_STATE_D0 && state == device->power.state) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] already in %s\n",
device->pnp.bus_id,
acpi_power_state_string(state)));
@@ -228,6 +241,30 @@ int acpi_device_set_power(struct acpi_device *device, int state)
if (result)
goto end;
}
+
+ if (device->power.state == ACPI_STATE_D0) {
+ int psc;
+
+ /* Nothing to do here if _PSC is not present. */
+ if (!device->power.flags.explicit_get)
+ return 0;
+
+ /*
+ * The power state of the device was set to D0 last
+ * time, but that might have happened before a
+ * system-wide transition involving the platform
+ * firmware, so it may be necessary to evaluate _PS0
+ * for the device here. However, use extra care here
+ * and evaluate _PSC to check the device's current power
+ * state, and only invoke _PS0 if the evaluation of _PSC
+ * is successful and it returns a power state different
+ * from D0.
+ */
+ result = acpi_dev_pm_explicit_get(device, &psc);
+ if (result || psc == ACPI_STATE_D0)
+ return 0;
+ }
+
result = acpi_dev_pm_explicit_set(device, ACPI_STATE_D0);
}