Re: Driver for pca9541 bus master selector

[Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>]

On Tue, 28 Sep 2010 09:07:46 -0700, Guenter Roeck wrote:
> On Tue, Sep 28, 2010 at 11:16:07AM -0400, Jean Delvare wrote:
> > Hi Guenter,
> > 
> > On Tue, 28 Sep 2010 07:33:02 -0700, Guenter Roeck wrote:
> > > I am in the process of writing a driver for the pca9541 bus master selector. 
> > > I using the i2c multiplexer framework, which fits the requirements quite nicely.
> > > 
> > > If anyone happens to know about an existing driver for this chip, please let me know.
> > > I would love to get some input for the arbitration mechanism needed to determine
> > > if and when to switch bus ownership from one master to the other.
> > 
> > See drivers/i2c/muxes/pca954x.c in 2.6.36-rc2 and later.
> > 
> Yes, I know. I use it as basis. But it doesn't support pca9541, unfortunately.

Oh, my bad. I had not noticed the PCA9541 was of a totally different kind.

> I use the select/deselect mechanism to trigger arbitration, but I still need
> a mechanism to communicate between the masters. After all, the problem to solve
> is that I have two masters and one slave, not one master and multiple slaves
> as with the other chips.
> 
> Note that I do have a solution which I think will work. Just figured it might
> save time if someone else already solved the same problem, and especially it 
> might help me to determine arbitration time constants. There was mention of
> a pca9541 driver several years ago, but I have not been able to find details.

-- 
Jean Delvare