diff options
| -rw-r--r-- | drivers/acpi/device_pm.c | 53 |
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); } |