[alsa-devel] [RFC] Initialize volumes of HD-audio slave ctls

Raymond Yau superquad.vortex2 at gmail.com
Fri Mar 9 00:04:23 CET 2012

2012/3/8, Takashi Iwai <tiwai at suse.de>:
> Hi,
> the patch below is an attempt to initialize the volume / mutes of
> slave controls (such as "Headphone", "Speaker") with vmaster in
> HD-audio, so that the sound can come out only by changing the master
> volume/mute.
> We have thought that such initializations could be done well in
> alsactl init, but it seems that not everyone installs the latest and
> greatest alsactl, and there is always a risk that any new controls may
> be added before alsactl is updated and released.  Since the master
> volume is set muted, the risk by this change should be low.
> patch_cirrus.c still doesn't support this because it's handling
> vmaster by itself, but it can be fixed later, too.
> If anyone has a concern by this, please let me know.

Can you explain the dB calculation of the volume controls when there
is a "virtual master" ?

The Documentation only mention that all the slaves must have the same dB range

There are codecs which only have "Headphone switch" but no "Headphone Volume"
(e.g. alc660) and some 4 channels codecs still not implemented (e.g.
ad1984 and ad1884) "Headphone Volume" control by using the extra DAC

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