On Mon, Aug 26, 2019 at 11:31:08AM +0300, Sakari Ailus wrote:
> 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;
Ick, no, this should be a bus-specific thing to handle such messed up
hardware. Why polute this in the driver core?
thanks,
greg k-h
