Dne 07. 11. 19 v 11:18 Cezary Rojewski napsal(a):
On 2019-11-05 20:36, 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.
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
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
Thanks for your work, Jaroslav.
However, I have some concerns here. First, could you elaborate on "we
require for the SOF kernel driver"?
Please, look here:
https://github.com/alsa-project/alsa-ucm-conf/commit/a8253465aef2df494ccd5b1103412b0318be582e#diff-a2ba34aee1a55c2fd664d78624477173L37
The HDA driver sometimes manages different JackControl names depending on the
used codec and it would be the real maintenance mess to use the DMI info (long
card name) for all possible configurations.
Also, if you look to the current configs, many duplications can be removed
with the If evaluations.
The substitutions and multi-instance support is probably warmly welcomed
by many, but "If" blocks are what worries me. Especially the nested
"Ifs". As Takashi pointed already out, UCM - which is currently is
viewed as a simple configuration syntax - is becoming a language on its
own. If we are to keep extending UCM on and on, we might as well switch
to JSON/ XML/ YAML entirely instead of developing our own thingy.
The configuration syntax itself is really close to JSON, it's just about the
run-time evaluation of some blocks at the load time. The different static
syntax format does not help us so much.
"If" block could just be what's needed to open new pandora box, allowing
for very complex and no longer easy-to-read config files. In general, if
one is to enlist an "If", why not define two UCMs instead?
For HDA, USB or and drivers with many hardware variants, the managing of
thousands of files will be the real nightmare. Also, at some point, I would
like to create the use case configs for all hardware, thus pulseaudio or any
other server (maybe pipewire in the future) can use the use case configuration
to abstract fully the hardware without their own profiles or so... The goal is
to have this in the one place.
Moreover, I see you mentioning the card-name dependency. This sounds
rather invasive. Separation of different config-versions would be required.
What do you mean with this?
Jaroslav
Czarek
--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
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