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

[Wookey]

+++ 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.

> (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.

Wookey
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