Re: how to define a 2-index control element?

[Abramo Bagnara <abramo@alsa-project.org>]

Takashi Iwai wrote:
> 
> so far, we have no way to distinguish the matrix elements from
> others.  imagine you implement all 1400+ elements as singletons.
> what happens if you run alsamixer on that?
> obviously showing all of them should be avoided.

Already now alsamixer does not show all the controls. What's the
problem?

> 
> > Your question is: how to represent the info that a set of elements may
> > (should) be organized in a matrix?
> >
> > We have already discussed that some time ago (about topology stuff,
> > etc., do you remember?) and we decided to keep out this mess from kernel
> > space.
> 
> yes.
> please note that my proposal is based on the current implementation.
> basically the matrix elements are mapped as 1:1 using a linear index
> just like others.  i proposed MATRIX_ELEM not to mix up it with other
> normal controls.  the mapping is done actually in alsa-lib.
> 
> > We decided to have (if needed) card specific alsa-lib code to handle all
> > that.
> 
> ok, the problems are
> 
> - showing all matrix elements on GUI as normal elements is
>   nonsense  -  there must be some flag to distinguish the matrix
>   elements from others even if we implement the matrix on a linear
>   array.
> 
> - we have no info to define the size of indices.
>   without this info, the general mapping code cannot be implemented on
>   the alsa-lib.

Card specific code may solve all that easily.

We need to separate in our minds the _basic_ hardware access and
layout/display consideration. Kernel is for the former, libraries and
applications for the latter.

-- 
Abramo Bagnara                       mailto:abramo@alsa-project.org

Opera Unica                          Phone: +39.546.656023
Via Emilia Interna, 140
48014 Castel Bolognese (RA) - Italy

ALSA project               http://www.alsa-project.org
It sounds good!

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