[alsa-devel] [PATCH] asoc tlv320aic3x: add GPIO support

[Daniel Mack]

On Sat, Apr 19, 2008 at 03:50:06PM +0100, Mark Brown wrote:
> > Ok, but why not let the codec driver expose all the functionality it can
> > offer for setting up a certain GPIO and use this alsa control either
> > from user space or from the asoc machine part? I think that's the most
> > flexible way at all, no?
> 
> The CODEC driver can't safely give user space control of multi-function
> pins in general, including GPIOs, since their usage depends very
> strongly on how they have been connected to the system.  At best much of
> the functionality won't be useful on a given board due to a lack of
> appropriate connections.  At worst the consequences of misusing them can
> include things like causing one or more chips in the system to fall
> over, perhaps even the entire system.  For example, if you've got two
> chips each trying to drive a signal to different voltages then it is
> possible that one or both of them will do something like attempt to
> consume too much power and cause supplies to collapse.

Ok, agreed to this point. I wanted to implement this feature as generic
as possbile, but you're right, that might cause some trouble.

> In the case of jack detect I'm actually currently working on a
> generalisation of that since it's such a common feature.  I hope to have
> something in the next week or two but it depends on my other work.

I attached a patch for a proprietary interface - is that what you were
talking about? Would that approach be mergeable with your generic jack
detect code?

Thanks and best regards,
Daniel


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