About ALSA dummy module: support customized mixer volume leveling

[Takashi Iwai]

On Thu, 08 Sep 2022 07:26:02 +0200,
YJ Lee wrote:
> 
> Hello Takashi (and the alsa community),
> 
> This is YJ Lee from chromium.org.
> 
> I'm thinking about extending the ALSA dummy module to support
> customized volume leveling. It will be very useful to test devices
> with different volume granularity. Currently this module is using
> hard-coded mixer volume leveling, from min=-50 to max=100.
> 
> See L716: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/tree/sound/drivers/dummy.c?h=queue/5.19#n716
> 
> My plan (A) is to expose 2 more additional module parameters and
> replace a few occurrences, from L742-750.
> 
> Another plan (B) is to leverage the current existing module
> parameter:model, and make the dummy-module to be able to accept models
> with customized volume leveling. New dummy models can be provided as
> configuration files, and be used in the same way as how currently
> existing dummy models (L146-213) are used. However, it's a bit
> over-engineering from the original purpose.
> 
> What do you think about these plans? Any insight you (and the alsa
> community) can provide will be greatly appreciated.

Only for volume min/max, module options may be an easier way, IMO.

OTOH, if we want to adjust more stuff, another possibility is to
extend the proc file.  It currently supports the dynamic changes of
PCM parameters, but we can extend it or add a new proc file for
adjusting other stuff, too.  So the question is what else we want to
allow changing.


thanks,

Takashi