Re: [RFC PATCH 0/3] introduce: Multistate Switch Class

[Mark Brown <broonie@opensource.wolfsonmicro.com>]

On Tue, Dec 06, 2011 at 06:38:34AM +1100, NeilBrown wrote:

> Ahh..
> So to try to restate the requirements:

>  A "cable-port" can detect when a "cable" in inserted (or removed) and can
>  determine the "cable-type" which comprises:
>    - a "cable-name" which is an arbitrary label interpreted in the context of
>      the particular port
>    - 1 or more "cable-function" flags which indicate what functions the 
>      cable support.  A given port has a fixed set of "cable-functions" and 
>      for any given cable it will report true/false (present/absent, on/off)
>      for each cable-function.
> 
>  This full "cable-type" needs to be presented to user-space, and individual
>  cable-functions may need to be communicated to specific drivers to trigger a
>  'probe' function.

Yes, that seems broadly sane for me.

> Questions:
>   1/ Do we need to communicate anything to drivers apart from "cable-detect"?
>      i.e. are they quite cable of probing and identifying, or do they need to
>      be told what to look for?

Perhaps.

>   2/ Does it hurt to simply wake up all drivers that might be listening on
>      the cable or do we need individual wake-ups (notifiers) for each
>      cable-function?

I suspect not.

>   3/ Does anything in the kernel care about the cable-name, or is that only
>      interesting to user-space?

I suspect not.

Other people may have other opinions, though.