[alsa-devel] UCM extensions

[Pierre-Louis Bossart]

On 11/5/19 1:36 PM, Jaroslav Kysela wrote:
> Hi all,
> 
>      I make some internal ucm code cleanups in alsa-lib and added three 
> major extensions to allow more complex configurations which we require 
> for the SOF kernel driver.

Great, thanks for working on this!

> 
>      The first thing is the added substitution for the value strings:
> 
> https://github.com/alsa-project/alsa-lib/commit/f1e637b285e8e04e6761248a070f58f3a8fde6fc 
> 
> 
>      The second thing is the If block:
> 
> https://github.com/alsa-project/alsa-lib/commit/985715ce8148dc7ef62c8e3d8ce5a0c2ac51f8df 

is it possible for the Condition to check if the card contains the SOF 
prefix?

For Baytrail/Cherrytrail support, we have a ton of existing UCM files, 
and the only thing needed is e.g.
- to change from hw:bytcrrt5640 to hw:sofbytcrt5640
- make the controls for the legacy driver conditional

SectionVerb {
	EnableSequence [
		
		if (card name does not contain SOF)
		<platforms/bytcr/PlatformEnableSeq.conf>
		endif
		<codecs/rt5640/EnableSeq.conf>
	]

Most of the information that matters for those UCM files is the type of 
peripherals and the matching mixer configuration for the codec driver, 
and we should reuse this information between legacy and SOF.

> 
>      The third thing is the card / hardware like specifier passed as the 
> ucm name to snd_use_case_mgr_open() to support multiple card instances:
> 
> https://github.com/alsa-project/alsa-lib/commit/60164fc5886cdc6ca55eeed0c2e3f751a7d2b2c0 
> 
> 
>      All those patches (with other cleanups) are in the ucm2 branch on 
> github for comments:
> 
> https://github.com/alsa-project/alsa-lib/commits/ucm2
> 
>      The proposed SOF UCM config diff is here:
> 
> https://github.com/alsa-project/alsa-ucm-conf/commit/723b6da881721488229154e923ed36413955a051 
> 
> https://github.com/alsa-project/alsa-ucm-conf/commits/ucm2
> 
>      I added everything to keep the interface backward compatible, so 
> the current applications should not observe any different behavior. The 
> applications like pulseaudio should use the 'hw:CARD_INDEX' specifier 
> for the open call in the future and snd_use_case_parse_ctl_elem_id() 
> helper for the element control names.
> 
>      If you have another ideas to address those issues, please, let me 
> know.
> 
>      BTW, Mark: The SOF UCM configs relies on the driver name changes, 
> so it might be worth to send "ASoC: intel - fix the card names" patch to 
> 5.4 to make things stable more quickly:
> 
>      https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git/commit/?h=for-5.5&id=d745cc1ab65945b2d17ec9c5652f38299c054649
> 
>                  Thanks,
>                      Jaroslav
>