On Wed, Sep 02, 2020 at 06:34:30PM +0200, Rafael J. Wysocki wrote: > On Wed, Sep 2, 2020 at 6:31 PM Sakari Ailus > <sakari.ailus@xxxxxxxxxxxxxxx> wrote: > > > > Hi Rafael, > > > > Thank you for the review. > > > > On Wed, Sep 02, 2020 at 05:57:01PM +0200, Rafael J. Wysocki wrote: > > > On Tue, Sep 1, 2020 at 11:03 PM Sakari Ailus > > > <sakari.ailus@xxxxxxxxxxxxxxx> wrote: > > > > > > > > Document the probe-low-power _DSD property and how it is used with I²C > > > > drivers. > > > > > > I would reorder the series to make this go right after the [1/6] or > > > maybe even fold it into that patch. > > > > > > The point is that the changes in [1/6] clearly depend on the property > > > defined here. > > > > Ack. > > > > > > > > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > > > > --- > > > > .../acpi/dsd/allow-low-power-probe.rst | 28 +++++++++++++++++++ > > > > Documentation/firmware-guide/acpi/index.rst | 1 + > > > > 2 files changed, 29 insertions(+) > > > > create mode 100644 Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst > > > > > > > > diff --git a/Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst b/Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst > > > > new file mode 100644 > > > > index 0000000000000..6fcc89162b898 > > > > --- /dev/null > > > > +++ b/Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst > > > > @@ -0,0 +1,28 @@ > > > > +.. SPDX-License-Identifier: GPL-2.0 > > > > + > > > > +====================================== > > > > +Probing I²C devices in low power state > > > > +====================================== > > > > + > > > > +Introduction > > > > +============ > > > > + > > > > +In some cases it may be preferred to leave certain devices powered off for the > > > > +entire system bootup if powering on these devices has adverse side effects, > > > > +beyond just powering on the said device. Linux recognizes the _DSD property > > > > +"allow-low-power-probe" that can be used for this purpose. > > > > > > It would be good to refer to the document defining the generic _DSD > > > properties mechanism and the GUID used for that from here. > > > > I'll add a reference to the device properties UUID for _DSD spec. > > > > > > > > The meaning of "_DSD property" may not be entirely clear to the > > > reader as it stands. > > > > > > And maybe call the property "i2c-allow-low-power-probe" or similar, to > > > indicate that it is specific to i2c. > > > > The bus determines that already, and it's only defined for I²C here. Should > > we need this in the future for e.g. I3C, there would be no need to think of > > renaming it, just changing the documentation and implementation. > > > > I don't have a strong opinion on that though. > > The point is that the property is not going to be recognized beyond i2c. Not right now, that is true. Sure, I can change it for v8. -- Sakari Ailus
