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

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Date:	Thu, 1 Dec 2011 13:51:05 +0900
From:	MyungJoo Ham <myungjoo.ham@...il.com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	NeilBrown <neilb@...e.de>, linux-kernel@...r.kernel.org,
	Linus Walleij <linus.walleij@...aro.org>,
	Arnd Bergmann <arnd@...db.de>,
	Mike Lockwood <lockwood@...roid.com>,
	Arve Hjønnevåg <arve@...roid.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Donggeun Kim <dg77.kim@...sung.com>, Greg KH <gregkh@...e.de>,
	Grant Likely <grant.likely@...retlab.ca>,
	Kalle Komierowski <karl.komierowski@...ricsson.com>,
	Johan PALSSON <johan.palsson@...ricsson.com>,
	Daniel WILLERUD <daniel.willerud@...ricsson.com>
Subject: Re: [RFC PATCH 0/3] introduce: Multistate Switch Class

On Thu, Dec 1, 2011 at 8:25 AM, Dmitry Torokhov
<dmitry.torokhov@...il.com> wrote:
> On Wed, Nov 30, 2011 at 11:17:41PM +0000, Mark Brown wrote:
>> On Thu, Dec 01, 2011 at 09:56:33AM +1100, NeilBrown wrote:
>> > On Wed, 30 Nov 2011 15:40:48 +0900 MyungJoo Ham <myungjoo.ham@...il.com>
>> > wrote:
>>
>> > > I'm focusing on an external connector or port that each physical port
>> > > may inhabit multiple cables at a time although it should support a
>> > > port that may inhabit a single cable only at a time. However, the
>> > > class could be used for other general "multistate mux" that connects
>> > > different device drivers.
>>
>> >  maybe I'm just slow, but I'm having a lot of trouble imagining a single port
>> >  that could have multiple cables plugged in at the same time.  And this
>> >  blockage is stopping me from reflecting usefully on your other points.
>>
>> >  Are you able to show me a picture or a diagram or something so I can
>> >  visualise what you are talking about?
>> >  To me: once you plug one cable into a port, it is full and there is no room
>> >  for any more cables.
>>
>> One obvious example is the sort of big multi-way docking connector that
>> many mobile devices have (iPod and friends being one of the most
>> common).  These are essentially the same as docking station connections
>> on a laptop in terms of what they bring out - a variety of audio, video
>> and communication connections - which may go to a docking station or
>> some kind of breakout or adaptor cable and may have sub-ports hanging
>> off them (eg, it's common for tablets to have docking stations with HDMI
>> and audio sockets on them).
>>
>> There are also lower pin count equivalents like the multiplexed "USB"
>> sockets on some phones which can also carry other functions with
>> adaptors, and even something like a headset is really a microphone and
>> headphones on a single jack.
>
> Physical jack does not have to map 1:1 on logical jack. So 1 physical
> docking connector can be represented by 1 logical video connector, line
> in, line out, microphone and maybe else.
>

Yes, we can implement that way.

However, the "mux" device (e.g., MAX8997 MUIC / MAX77693 / FSA9480 /
... / and some multipurpose earphone jacks maybe? ) still needs to
have one device driver to represent the physical jack; it has one IRQ,
one set of power controls, and one set of registers for all of these
connectors.


Cheers!
MyungJoo

> --
> Dmitry



-- 
MyungJoo Ham, Ph.D.
Mobile Software Platform Lab, DMC Business, Samsung Electronics
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