From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: Re: Driver for pca9541 bus master selector Date: Wed, 29 Sep 2010 09:19:28 +0200 Message-ID: <20100929091928.16256bb7@endymion.delvare> References: <20100928143302.GA7593@ericsson.com> <20100928171607.395f7736@endymion.delvare> <20100928160746.GB7976@ericsson.com> <20100928184215.00f82717@endymion.delvare> <20100928171627.GA8415@ericsson.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100928171627.GA8415-IzeFyvvaP7pWk0Htik3J/w@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Guenter Roeck Cc: "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Michael Lawnick , Rodolfo Giometti List-Id: linux-i2c@vger.kernel.org On Tue, 28 Sep 2010 10:16:27 -0700, Guenter Roeck wrote: > On Tue, Sep 28, 2010 at 12:42:15PM -0400, Jean Delvare wrote: > > Oh, my bad. I had not noticed the PCA9541 was of a totally different kind. > > Actually, I fell into the same trap. I was quite happy that someone else wrote > the driver for me ... until I realized that the chips solve the opposite problem. > > Time goes by ... have a look at > > http://lists.lm-sensors.org/pipermail/lm-sensors/2004-June/008023.html I didn't remember that discussion (unsurprisingly.) > I wasn't sure if you (or someone else) ever had a driver for 9541, or if you referred > to 9540 in above post. The links in the post don't work anymore. 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. 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. -- Jean Delvare