From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: Driver for pca9541 bus master selector Date: Wed, 29 Sep 2010 06:54:01 -0700 Message-ID: <20100929135401.GA11771@ericsson.com> References: <20100928143302.GA7593@ericsson.com> <20100928171607.395f7736@endymion.delvare> <20100928160746.GB7976@ericsson.com> <20100928184215.00f82717@endymion.delvare> <20100928171627.GA8415@ericsson.com> <20100929091928.16256bb7@endymion.delvare> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: <20100929091928.16256bb7-R0o5gVi9kd7kN2dkZ6Wm7A@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jean Delvare Cc: "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Michael Lawnick , Rodolfo Giometti List-Id: linux-i2c@vger.kernel.org On Wed, Sep 29, 2010 at 03:19:28AM -0400, Jean Delvare wrote: [ ... ] > > I was speaking of the PCA9540. I don't think anyone ever wrote a driver > for the PCA9541. And in all honestly I don't think the new i2c-mux > infrastructure is ready for this. It was written with single-master > topologies in mind. You'll have to rethink a lot of things if you want > to add support for "inverted" multiplexers. And I don't have the time > to help, sorry. > Actually, the infrastructure works quite nicely. I use select_chan to acquire the slave, and release_chan to initiate release. It behaves like a one-channel multiplexer. > I don't quite see the point of such chips, BTW. I2C supports > multi-master already, so two masters talking to the same slave > sequentially is already supported. > Tell that to our HW team, and to them: http://www.lineagepower.com/oem/pdf/CPLI2C.pdf Guenter