From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: Re: [RFC][PATCH] Enable async suspend/resume of i2c devices Date: Thu, 7 Apr 2011 10:25:44 +0200 Message-ID: <20110407102544.4c34dfeb@endymion.delvare> References: <20110406095240.410b4e7e@endymion.delvare> <20110406223123.GA5297@opensource.wolfsonmicro.com> <20110407095513.4c0b708e@endymion.delvare> <20110407080042.GF14519@opensource.wolfsonmicro.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110407080042.GF14519-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Brown Cc: Sonny Rao , "Rafael J. Wysocki" , Alan Stern , linux-pm-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Ben Dooks List-Id: linux-i2c@vger.kernel.org On Thu, 7 Apr 2011 09:00:43 +0100, Mark Brown wrote: > 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. Out of curiosity, how is this handled in the synchronous suspend/resume case? -- Jean Delvare