On Friday, May 10, 2019 12:09:26 PM CEST 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 | 9 +++++++--
> include/linux/device.h | 6 ++++++
> 2 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
> index b859d75eaf9f6..ca2409a30d26d 100644
> --- a/drivers/acpi/device_pm.c
> +++ b/drivers/acpi/device_pm.c
> @@ -1225,7 +1225,9 @@ 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 &&
> + !(dev->driver->probe_powered_off &&
> + device_property_present(dev, "avoid-power-probe"))) {
> /*
> * If the device's PM QoS resume latency limit or flags
> * have been exposed to user space, they have to be
> @@ -1273,7 +1275,10 @@ 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 &&
> + !(dev->driver->probe_powered_off &&
> + device_property_present(dev, "avoid-power-probe"))) {
> acpi_dev_pm_full_power(adev);
> acpi_device_wakeup_disable(adev);
> }
> diff --git a/include/linux/device.h b/include/linux/device.h
> index e85264fb66161..2a459fd5b954a 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -245,6 +245,11 @@ enum probe_type {
> * @owner: The module owner.
> * @mod_name: Used for built-in modules.
> * @suppress_bind_attrs: Disables bind/unbind via sysfs.
> + * @probe_powered_off: The driver supports its probe function being called while
> + * the device is powered off, 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.
> * @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.
> @@ -282,6 +287,7 @@ struct device_driver {
> const char *mod_name; /* used for built-in modules */
>
> bool suppress_bind_attrs; /* disables bind/unbind via sysfs */
> + bool probe_powered_off;
This is a bit of a misnomer IMO, because it is not just about devices that are completely off.
>From the ACPI perspective that is about all devices not in D0, which may mean gated clocks
etc.
I would call it probe_low_power or similar and analogously in patch [2/5], and apart from this
I have no objections against this series, but I would suggest to CC the next iteration of it
to Greg K-H and the LKML as it touches the driver core.
> enum probe_type probe_type;
>
> const struct of_device_id *of_match_table;
>
