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From: Arnd Bergmann <arnd@arndb.de>
To: myungjoo.ham@gmail.com
Subject: Re: [RFC PATCH 0/3] introduce: Multistate Switch Class
Date: Fri, 25 Nov 2011 14:02:27 +0000
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Cc: linux-kernel@vger.kernel.org, Mike Lockwood <lockwood@android.com>,
        Arve =?iso-8859-1?q?Hj=F8nnev=E5g?= <arve@android.com>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Donggeun Kim <dg77.kim@samsung.com>, Greg KH <gregkh@suse.de>,
        Linus Walleij <linus.walleij@linaro.org>
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On Thursday 24 November 2011, MyungJoo Ham wrote:
> For switch ports, which may have different types of cables
> (USB, TA, HDMI, Analog A/V, and others), we often have seperated device
> drivers that detect the state changes at the port and device drivers that
> do something according to the state changes.
> 
> For example, when MAX8997-MUIC detects a Charger cable insertion, another
> device driver (such as MAX8903 charger, MAX8997 charger, Charger Manager,
> or board file) needs to set charger current limit accordingly and when
> MAX8997-MUIC detects a HDMI cable insertion, multimedia device drivers
> need to do some operations accordingly.
> 
> This patchset supports the usage of notifier for passing such information
> between device drivers.
> 
> Another issue is that at a single switch port, there might be multiple
> and heterogeneous cables attached at the same time. Besides, the state
> (Attached or Detached) of each cable may alter independently.
> 
> In order to address such issues, Android kernel's "Switch" class seems to
> be a good basis and we have implemented "Multistate Switch Class" based on
> it. The "Switch" class code of Android kernel is GPL as well.

How does this relate to the new "pinmux" subsystem that Linus Walleij
maintains? Would it be useful to integrate your driver into pinmux
instead of starting a new subsystem?

	Arnd