From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: Driver for pca9541 bus master selector Date: Thu, 30 Sep 2010 00:48:47 -0700 Message-ID: <20100930074847.GA17693@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> <20100929135401.GA11771@ericsson.com> <4CA42750.5020500@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: <4CA42750.5020500-Mmb7MZpHnFY@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Michael Lawnick Cc: Jean Delvare , "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Rodolfo Giometti List-Id: linux-i2c@vger.kernel.org On Thu, Sep 30, 2010 at 01:59:44AM -0400, Michael Lawnick wrote: [ ... ] > I only took a rough look, but it seemed to me that the pca is part of > the main device. Yes > From abstraction side of view your problem seems a matter of > synchronization of two independent computer systems. You will need a > shared resource. The access to it could either be part of driver code or > by introducing a 'one-channel multiplexer' as you did. But the sync > needs to be done by your code via a shared data object. > Actually, the pca9541 has a bit in its register set which I can use. See NTESTON in its control register. That is visible as interrupt status at the other master. That is all I need, and reduces complexity significantly. Thanks, Guenter