[alsa-devel] Question about snd_mixer_selem_get_playback_dB_range()

Raymond Yau superquad.vortex2 at gmail.com
Mon Mar 21 14:43:03 CET 2011

2011/3/21 Tanu Kaskinen <tanu.kaskinen at digia.com>

> Hi,
> I have added code to Pulseaudio that checks that the kernel driver
> returns the same values if I call
> snd_mixer_selem_get_playback_dB_range() or
> snd_mixer_selem_ask_playback_vol_dB() with the lowest and highest volume
> steps. The reason I do this is that I've seen a driver that didn't
> return correct values from _dB_range() (it's fixed nowadays), so it's
> possible that the same kind of bugs will be seen in the future too.
> Doing this check at Pulseaudio startup helps to detect such bugs early.
> My question is about the case where the lowest volume step is mute. Is
> it a bug in the driver if _dB_range() returns something else than
> SND_CTL_TLV_DB_GAIN_MUTE as the min gain in such case?
AFAIK , only those STAC920x codec has SND_CTL_TLV_DB_GAIN_MUTE

most driver does not has min dB mute as the alsa driver just use the values
in the datasheet of most codec and DAC

So it is not any driver bug

I guess why the volume slider of gnome volume control is mute at mint is
just follow the behaviour of those OSS driver

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