[alsa-devel] TLV question - ranges not in volume order
tiwai at suse.de
Wed May 8 14:14:26 CEST 2013
At Wed, 08 May 2013 14:09:31 +0200,
Clemens Ladisch wrote:
> David Henningsson wrote:
> > I recently came across a strange ASoC volume control. In this case,
> > the values are not in volume order, i e, the control is declared
> > something like below.
> > However alsamixer seems not to handle this "reordering" correctly. My
> > question is if this is something that should be fixed in alsamixer (or
> > possibly alsa-lib?), or does one need to write some kind of mapping
> > table in the kernel, just to make something come in volume order to
> > userspace?
> Items in a DB_RANGE container must be ordered by their values *and* by
> their dB values. This implies that larger values must correspond with
> larger dB values, whis is also required for all other mixer controls.
> If the register values are unordered, the driver must reorder them.
Yep. Although there is no explicit definition, it's an implicit rule,
as we have never implemented the parser code to allow the disorder.
We should add a text mentioning that somewhere. A patch is welcome ;)
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