[PATCH 11/13] [ARM] pxa/balloon3: PCF857x GPIO expander and LEDs

[Marek Vasut]

Dne Pá 30. července 2010 14:36:09 Marek Vasut napsal(a):
> Dne Pá 30. července 2010 11:39:40 Wookey napsal(a):
> > +++ Marek Vasut [2010-07-30 06:44 +0200]:
> > > Dne Čt 29. července 2010 12:00:41 Wookey napsal(a):
> > > > +++ Marek Vasut [2010-07-29 05:16 +0200]:
> > > > > Add supported for PCF8574A GPIO expander and LEDs attached to it.
> > > > 
> > > > This IO board is an add-on used in some ballon configurations, not
> > > > part of the core board. There needs to be some way of selecting this
> > > > support when the loon is used in this configuration. We have the
> > > > balloon_has() macro which is used for dealing with the different
> > > > builds of the board itself. Perhaps it should be extended to deal
> > > > with add-on board functionality too?
> > > > 
> > > > More obvious is using the CONFIG system to just enable this if
> > > > CUED_IO_BOARD is configured.
> > > 
> > > You can just disable the PCF driver if you want to save space. In case
> > > you won't have the CUED board connected, the driver will just fail to
> > > probe so it's ok I believe.
> > > 
> > > The macro could be extended, but do we want such a weird stuff in
> > > kernel?
> > 
> > That was how this list suggested we deal with the unprobe-able build
> > variation, I beleive.
> 
> We have loadable kernel modules ever since ... long time ago. Maybe that's
> more like the way to go.
> 
> > > (especially if the driver can simply fail to probe).
> > 
> > No. Clearly anything that is probe-able should be probed. I thought
> > thtat this wouldn't be as I2C devices are pretty dumb, but I guess we
> > know its address here so we can try it and if no response then it's
> > not there.
> 
> Yes, this one is probeable.

Re-adding Eric as he was dropped. Cheers
> 
> Cheers
> 
> > Wookey