From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mark Brown <broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
Subject: Re: [RFC][PATCH] Enable async suspend/resume of i2c devices
Date: Thu, 7 Apr 2011 09:00:43 +0100
Message-ID: <20110407080042.GF14519@opensource.wolfsonmicro.com>
References: <20110406095240.410b4e7e@endymion.delvare> <Pine.LNX.4.44L0.1104061043220.1907-100000@iolanthe.rowland.org> <20110406223123.GA5297@opensource.wolfsonmicro.com> <20110407095513.4c0b708e@endymion.delvare>
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To: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
Cc: Sonny Rao <sonnyrao-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, "Rafael J. Wysocki" <rjw-KKrjLPT3xs0@public.gmane.org>, Alan Stern <stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org>, linux-pm-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Ben Dooks <ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org>
List-Id: linux-i2c@vger.kernel.org

On Thu, Apr 07, 2011 at 09:55:13AM +0200, Jean Delvare wrote:
> On Thu, 7 Apr 2011 07:31:24 +0900, Mark Brown wrote:

> > You definitely don't know *anything* about the relationships for I2C,
> > especially in embedded systems.

> Can you please elaborate? The i2c subsystem uses a standard
> parent-children relationship. It seems fairly similar to USB for
> example. The only special case I can think of is with bus multiplexing,
> but it would be easy enough to switch off async suspend/resume in this
> case.

For I2C itself that's the case but for power and GPIO (which are very
common in conjunction with I2C in the embedded context) we loose the
tree.  This is much less of an issue with buses like PCI where
everything is bundled into the bus.