[alsa-devel] link between HDMI ELD and PCM devices

[Pierre-Louis Bossart]

> GeForce 520 (1 codec, up to 4 pins per, but 2 pins disabled):
> 
> [swarren at swarren-lx2 alsa-driver-build]$ sudo amixer -c1 controls | grep ELD
> numid=5,iface=PCM,name='ELD',device=3
> numid=10,iface=PCM,name='ELD',device=7
> 
> GeForce 200 series (4 codecs, 1 pin per):
> 
> [swarren at swarren-lx2 alsa-driver-build]$ sudo amixer -c2 controls | grep ELD
> numid=5,iface=PCM,name='ELD',device=3
> numid=10,iface=PCM,name='ELD',device=7
> numid=15,iface=PCM,name='ELD',device=8
> numid=20,iface=PCM,name='ELD',device=9
> 
> That looks pretty sane to me.

Excellent. Thanks for your time!

> It doesn't apply to ToT; it conflicts slightly with Takashi's recent
> ELD bytes cleanup.

Ah, yes. Haven't updated since kernel.org went down.

> 	pin_idx = kcontrol->private_value; 
> ...
> > +	if (pin_idx < 0) {
> > +		uinfo->count = 0;
> 
> I don't think you need that conditional. I'd just assume that pin_idx
> was set correctly when the control was created, and not create the
> control if that wasn't the case. At most, BUG_ON here?

Agree. All this was copy/pasted debug code in case I modified things.

> One question: How do we know that ucontrol is large enough to accept
> eld->eld_size; are all BYTES controls always big enough, or do we need
> a check here on ucontrol->value.bytes.size or something like that?

The ELD is limited to 256 bytes. Same as the size of a BYTES control.