[alsa-devel] Where is simple mixer control "Surround" defined for ac97 or via82xx? I cant find it anywhere in ac97....

Clemens Ladisch cladisch at fastmail.net
Fri Aug 10 09:33:46 CEST 2007

John L. Utz III wrote:
> amixer controls | grep Surround
> numid=20,iface=MIXER,name='Surround Playback Switch'
> numid=21,iface=MIXER,name='Surround Playback Volume'
> But for the life of me, i cant find the code that implements it!

Around line 1350 in ac97_codec.c:

	/* build surround controls */
	if ((snd_ac97_try_volume_mix(ac97, AC97_SURROUND_MASTER))
		&& !(ac97->flags & AC97_AD_MULTI)) {
		/* Surround Master (0x38) is with stereo mutes */
		if ((err = snd_ac97_cmix_new_stereo(card, "Surround Playback",
						    AC97_SURROUND_MASTER, 1, 0,
						    ac97)) < 0)
			return err;


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