Re: [PATCH v4 5/6] at24: Support probing while off

From: Bartosz Golaszewski
Date: Mon Aug 10 2020 - 14:12:17 EST

On Mon, Aug 10, 2020 at 10:26 AM Sakari Ailus <sakari.ailus@xxxxxx> wrote:


> >
> > Rafael: I think that there are two issues with patch 1/5:
> > 1. It adds a very specific boolean flag to a structure that's meant to
> > be very general. As I pointed out in the i2c patch: at the very least
> > this could be made into an int storing flag values, instead of a
> > boolean field. But rather than that - it looks to me more like a
> > device (or bus) feature than a driver feature. Is there any ACPI flag
> > we could use to pass this information to the driver model without
> > changing the driver structure?
> To my knowledge there isn't. The fact that I²C devices are powered on for
> probe in ACPI based systems is specific to Linux kernel and not ACPI as
> such.
> The reason this needs to be in a generic struct is that the device's power
> state will be changed before any interaction with the driver takes place as
> it's the I²C framework that powers on the device.

I'm not sure I'm following. Looking at patch 1/6 struct device already
exists so why can't this information be conveyed "per device" as
opposed to "per driver"?