Allow drivers and firmware tell ACPI that there's no need to power on a
device for probe. This requires both a hint from the firmware as well as
an indication from a driver to leave the device off.
Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
---
drivers/acpi/device_pm.c | 15 +++++++++++++--
include/linux/device.h | 7 +++++++
2 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index f616b16c1f0be..adcdf78ce4de8 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -1276,7 +1276,12 @@ static void acpi_dev_pm_detach(struct device *dev, bool power_off)
if (adev && dev->pm_domain == &acpi_general_pm_domain) {
dev_pm_domain_set(dev, NULL);
acpi_remove_pm_notifier(adev);
- if (power_off) {
+ if (power_off
+#ifdef CONFIG_PM
+ && !(dev->driver->probe_low_power &&
+ device_property_present(dev, "probe-low-power"))
+#endif
+ ) {
/*
* If the device's PM QoS resume latency limit or flags
* have been exposed to user space, they have to be
@@ -1324,7 +1329,13 @@ int acpi_dev_pm_attach(struct device *dev, bool power_on)
acpi_add_pm_notifier(adev, dev, acpi_pm_notify_work_func);
dev_pm_domain_set(dev, &acpi_general_pm_domain);
- if (power_on) {
+
+ if (power_on
+#ifdef CONFIG_PM
+ && !(dev->driver->probe_low_power &&
+ device_property_present(dev, "probe-low-power"))
+#endif
+ ) {
acpi_dev_pm_full_power(adev);
acpi_device_wakeup_disable(adev);
}
diff --git a/include/linux/device.h b/include/linux/device.h
index 6717adee33f01..4bc0ea4a3201a 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -248,6 +248,12 @@ enum probe_type {
* @owner: The module owner.
* @mod_name: Used for built-in modules.
* @suppress_bind_attrs: Disables bind/unbind via sysfs.
+ * @probe_low_power: The driver supports its probe function being called while
+ * the device is in a low power state, independently of the
+ * expected behaviour on combination of a given bus and
+ * firmware interface etc. The driver is responsible for
+ * powering the device on using runtime PM in such case.
+ * This configuration has no effect if CONFIG_PM is disabled.
* @probe_type: Type of the probe (synchronous or asynchronous) to use.
* @of_match_table: The open firmware table.
* @acpi_match_table: The ACPI match table.
@@ -285,6 +291,7 @@ struct device_driver {
const char *mod_name; /* used for built-in modules */
bool suppress_bind_attrs; /* disables bind/unbind via sysfs */
+ bool probe_low_power;
enum probe_type probe_type;
const struct of_device_id *of_match_table;
--
2.20.1
