Re: [PATCH v6 1/6] i2c: Allow an ACPI driver to manage the device's power state during probe

[Sakari Ailus]

On Mon, Aug 31, 2020 at 11:31:09AM +0200, Wolfram Sang wrote:
> 
> > This patchset is really about changing the default of ACPI powering up I²C
> > devices. On OF the drivers are indeed responsible for that.
> 
> So, maybe it makes sense then to move from 'device_property_present()'
> to 'acpi_dev_get_property()' or something alike? To clearly tell this

I'll do that for v7 soon.

> binding is expected to be used with ACPI only. Then, we can skip this
> discussion now and postpone it to when someone wants to use it with DT.
> Which is hopefully never. Or does this approach have drawbacks?

The same issue in principle could be there on DT, too, as the cameras are
the same. There are a few sensor drivers supporting DT that currently don't
access the device in probe to avoid having to power it on. For cameras I
suppose that's just fine but I'd be hesitant changing the behaviour of e.g.
the at24 driver to support that use case without making it somehow
configurable.

> 
> > My original series had a field in struct device_driver for this purpose but
> > Greg K-H suggested moving it to I²C instead:
> > 
> > <URL:https://lore.kernel.org/linux-acpi/20190826084343.GA1095@xxxxxxxxx/>
> 
> Ok, we can still factor it out in the unlikely case it needs to be done
> again.
> 
> I still have the question via which tree this should go upstream?
> It is probably more I2C than ACPI?

I think so.

Rafael, would you be fine with this set being merged through the I²C tree?
There's a single patch adding an ACPI function there.

-- 
Sakari Ailus