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Date: Wed, 30 Nov 2011 09:46:09 +0000
From: Mark Brown <broonie@opensource.wolfsonmicro.com>
To: MyungJoo Ham <myungjoo.ham@gmail.com>
Cc: Greg KH <gregkh@suse.de>, Dmitry Torokhov <dmitry.torokhov@gmail.com>,
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        Daniel WILLERUD <daniel.willerud@stericsson.com>
Subject: Re: [RFC PATCH 0/3] introduce: Multistate Switch Class
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On Wed, Nov 30, 2011 at 03:58:54PM +0900, MyungJoo Ham wrote:
> On Wed, Nov 30, 2011 at 3:35 PM, Greg KH <gregkh@suse.de> wrote:

> > Actually, why can't we just use gpio as-is here and just treat these
> > devices as "generic" i/o "pins"?

> For userspace, GPIO should work.

> For device drivers, I'm not sure.

> In order to work for device drives, a GPIO event (GPIO Input goes L->H
> or H->L) should trigger events in other device drivers. The GPIO value
> can be set by the external-connector/multistate-switch driver
> (notifier) based on its own interrupts.

We also need some way to group things together so that we can understand
that we've got a single connector that can detect multiple things (eg,
understanding that a cable hsa audio and video capability).