Re: Driver for pca9541 bus master selector

[Guenter Roeck <guenter.roeck-IzeFyvvaP7pWk0Htik3J/w@public.gmane.org>]

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.
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.

Thanks,
Guenter