On Tue, Jan 21, 2020 at 10:09 AM Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> wrote: > > Hi Rafael, > > Thank you for the review. > > On Mon, Jan 13, 2020 at 11:41:12AM +0100, Rafael J. Wysocki wrote: > > On Thu, Jan 9, 2020 at 4:44 PM Sakari Ailus > > <sakari.ailus@xxxxxxxxxxxxxxx> wrote: > > > > > > Add a convenience function to tell whether a device is suspended for probe > > > or remove, for busses where the custom is that drivers don't need to > > > resume devices in probe, or suspend them in their remove handlers. > > > > > > Returns false on non-ACPI systems. > > > > > > Suggested-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > > > --- > > > drivers/acpi/device_pm.c | 35 +++++++++++++++++++++++++++++++++++ > > > include/linux/acpi.h | 5 +++++ > > > 2 files changed, 40 insertions(+) > > > > > > diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c > > > index 5e4a8860a9c0c..87393020276d8 100644 > > > --- a/drivers/acpi/device_pm.c > > > +++ b/drivers/acpi/device_pm.c > > > @@ -1348,4 +1348,39 @@ int acpi_dev_pm_attach(struct device *dev, bool power_on) > > > return 1; > > > } > > > EXPORT_SYMBOL_GPL(acpi_dev_pm_attach); > > > + > > > +/** > > > + * acpi_dev_low_power_state_probe - Tell if a device is in a low power state > > > > "Check the current ACPI power state of a device." > > Sounds good. > > > > > > + * during probe > > > > Why is this limited to probe? > > Well.. that was the purpose. It could be used at other times, too, I guess, > but most of the time runtime PM is the right interface for doing that. PM-runtime is a layer above this one. It is mostly about the coordination between devices, reference counting etc which this is about device power states. > > > > The function actually checks whether or not the ACPI power state of > > the device is low-power at the call time (except that it is a bit racy > > with respect to _set_power(), so it may not work as expected if called > > in parallel with that one). > > > > Maybe drop the "probe" part of the name (actually, I would call this > > function acpi_dev_state_low_power()) and add a paragraph about the > > potential race with _set_power() to the description? > > Agreed, I'll use the text you provided below. > > > > > > + * @dev: The device > > > > "Physical device the ACPI power state of which to check". > > Ok. > > > > > > + * > > > + * Tell whether a given device is in a low power state during the driver's probe > > > + * or remove operation. > > > + * > > > + * Drivers of devices on certain busses such as I涎 can generally assume (on > > > + * ACPI based systems) that the devices they control are powered on without > > > + * driver having to do anything about it. Using struct > > > + * device_driver.probe_low_power and "probe-low-power" property, this can be > > > + * negated and the driver has full control of the device power management. > > > > The above information belongs somewhere else in my view. > > How about putting it to the DSD ReST property documentation, perhaps with a > little bit more context? I can add another patch for that. Yes, something like that.
