Re: what does struct snd_ac97_build_ops do? suspect i need a new one for the via1618 to get Surround to work

[Takashi Iwai <tiwai@suse.de>]

At Fri, 19 Jan 2007 15:49:24 -0800,
John Utz wrote:
> 
> Hello;
> 
> I have an MSI CN700T ITX motherboard with a VIA 8237 SouthBridge and a VIA 1618 codec.
> 
> Using aplay and speakertest, 2 channel sound works well, but 6ch sound with the ever
> popular chan-id.wav* produces no output.
> 
> However, neither aplay nor speakertest *fail* when attempting to write to the other
> channels so they evidently exist, but may be muted.
> 
> I went to the trouble of installing windows and the VIA Vinyl driver for same and
> after I used the via configuration app to set the mic and line inputs to be C/LFE and
> Rr outs, I received the expected output.
> 
> Is 1618 6ch expected to work with ALSA 1.0.13?

... only if the codec chip works without extra adjustment.
(In other words: most likely it doesn't work as it is.)


> based on looking at ac97_codec.c: static const struct ac97_codec_id snd_ac97_codec_ids
> ,
> 
>  it seems to be stubbed out instead of fully implemented:
> 
> { 0x56494182, 0xffffffff, "VIA1618", NULL, NULL },
> 
> My suspicion is that I need to create the following items (hx3rd from the vt1616
> versions):
> 
> static const struct snd_kcontrol_new snd_ac97_controls_vt1618
> 
> static int patch_vt1618_specific(struct snd_ac97 * ac97)
> 
> static struct snd_ac97_build_ops patch_vt1618_ops
> 
> int patch_vt1618(struct snd_ac97 * ac97)
> 
> Am I correct in my assumptions? If so, what do these 2 arrays and 2 functions actually
> do?

They set up codec-specific things and create codec-specific controls.

Honestly, I cannot tell any exact thing unless I get a datasheet of
this codec chip.  VT1616 and 1617 have totally different configs,
AFAIK...


Takashi

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