From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: Re: Problem with multiple i2c multiplexers on one bus, and mux bus naming Date: Sun, 17 Nov 2013 21:31:23 +0100 Message-ID: <20131117213123.57920de0@endymion.delvare> References: <5287B9E4.1020107@roeck-us.net> <20131116214116.3d035b76@endymion.delvare> <5288FB94.6000304@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5288FB94.6000304-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Guenter Roeck Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org On Sun, 17 Nov 2013 09:23:32 -0800, Guenter Roeck wrote: > I think it would still be unique name, as long as the parent adapter number > is well defined (which it hopefully is). At least with the change I can > 1) identify the mux and 2) walk back in the tree of i2c adapters to find > the root. Using above example, I know that i2c-2-mux (chan_id 0) is on bus 2. > Bus 2 is i2c-0-mux (chan_id 0), so I know it is connected to bus 0. > > Am I missing something ? You're not missing anything. It is indeed possible to "resolve" the name to uniqueness. My only concern is that someone has to do it, and for example libsensors currently doesn't. The configuration file parser would have to be extended to do that resolution in order to fully support chip-instance-specific configuration statements on multiplexed topologies. Same goes for i2c-tools: normally you can pass the bus by name instead of number, but with the need to resolve the name of muxed branches, this no longer works. I'm not saying this is a blocker problem, just something to keep in mind. -- Jean Delvare