Re: [RFC 00/10] add support for fwnode in i2c mux system and sfp

Mark Brown
2022-02-24T18:40:16Z

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On Thu, Feb 24, 2022 at 08:14:51PM +0200, Sakari Ailus wrote:
> On Thu, Feb 24, 2022 at 03:33:12PM +0000, Mark Brown wrote:

> > I believe clocks are also potentially problematic for similar reasons
> > (ACPI wants to handle those as part of the device level power management
> > and/or should have native abstractions for them, and I think we also
> > have board file provisions that work well for them and are less error
> > prone than translating into an abstract data structure).

> Per ACPI spec, what corresponds to clocks and regulators in DT is handled
> through power resources. This is generally how things work in ACPI based
> systems but there are cases out there where regulators and/or clocks are
> exposed to software directly. This concerns e.g. camera sensors and lens
> voice coils on some systems while rest of the devices in the system are
> powered on and off the usual ACPI way.

But note crucially that when these things are controlled by the OS they
are enumerated via some custom mechanism that is *not* _DSD properties -
the issue is with the firmware interface, not with using the relevant
kernel APIs in the client or provider devices.

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