Re: [alsa-devel] [RFC] ucb1400 touchscreen, irq auto probing and ac97 with its private field

[Takashi Iwai <tiwai@suse.de>]

At Thu, 24 Apr 2008 15:57:52 +0100,
Mark Brown wrote:
> 
> On Thu, Apr 24, 2008 at 04:04:59PM +0200, Sebastian Siewior wrote:
> 
> > I've sent a RFC to the alsa mailing list [1] about adding an extra field in
> > order to pass the IRQ from the AC97 driver to the ucb1400 driver. The
> > result was:
> 
> > Now I'm curious what solution the people here prefer:
> > - adding a private field [1] (my favorite)
> 
> As I indicated in reply to your initial RFC any such private field
> ought to be a void * in order to allow other information to be passed
> through to drivers.

The problem with void * is that you don't know what it really is.
Yes, it's exactly the purpose - to be generic.  But, this means that
the true shape of the tossed data from the ac97 controller driver to
the platform driver is anonymous, too.

So, from that perspective, I find 'int irq' better to assure a strong
binding.  Of course, if there are more other use cases, this argument
doesn't apply well.

> Note that this will also need changes in all the relevant AC97 drivers
> to support getting the private data from platform/machine definition
> code to the relevant driver using whatever methods are appropriate for
> the platform.

What kind of data are needed be passed?


thanks,

Takashi