Re: Re: Assign line names at runtime

[Kent Gibson <warthog618@gmail.com>]

On Fri, Jan 12, 2024 at 01:16:29PM +0000, Westermann, Oliver wrote:
>
>
> On Fri, Jan 12, 2024 at 1:31 AM Kent Gibson wrote:
> > So I'm at the point that I think we could do it, one way or another, but
> > much less certain if we should.
> > I would not consider it if there was an alternative.
>
> I played around a bit this morning and I have a (probably hacky but) working
> prototype which adds a GPIO_V2_SET_LINEINFO_IOCTL and currently only allows to
> override a line name. I played around a bit and tried to break something, but
> currently, it seems to work. But I'm also open for any alternative, so maybe
> with some extra info, somebody has better ideas:
>
> The hardware variants I'm dealing with could be considered accessories:
> Extension of a base in different kind and revisions. As those, they are mostly
> not boot critical - I can defer probing. That would also allow me to defer
> probing up until manual probing from userspace, eg by a udev rule collecting
> more data and providing that to the driver once all data is present.
>
> Could e.g. an extension of the modprobe params for i2c gpiochip drivers allow to
> provide not only bus and address, but also a list of pin names? Ideally
> implemented on the gpiochip / i2c gpio level so this applies to all gpio drivers?
>
> (new attempt at manual formatting, sorry)
>

Sorry for the belated reply, but just to clarify where I am with this:

This looks like an init-time problem, more so than a runtime, so you
should pursue the init-time solutions and exhaust your options there
before looking to solve it via the GPIO uAPI.

Cheers,
Kent.