Re: [PATCH] ASoC: core: Change device numbering

[Jaroslav Kysela <perex@perex.cz>]

On 27. 01. 25 15:45, Amadeusz Sławiński wrote:
> On 1/27/2025 3:44 PM, Amadeusz Sławiński wrote:
>> Currently ASoC cards when enumerating create CPUs rtds first and CODECs
>> rtds second. This causes device number on cards to not start from 0, but
>> from number of present CPUs. During that it does count number of rtds
>> and uses it as device number visible in userspace.
>>
>> This patch changes device visible to userspace, when listing cards:
>>
>> Before:
>> card 0: hdaudioB0D0 [hdaudioB0D0], device 1: HDAudio Analog (*) []
>> card 1: hdaudioB0D2 [hdaudioB0D2], device 1: HDMI1 (*) []
>> card 1: hdaudioB0D2 [hdaudioB0D2], device 2: HDMI2 (*) []
>> card 1: hdaudioB0D2 [hdaudioB0D2], device 3: HDMI3 (*) []
>>
>> After:
>> card 0: hdaudioB0D0 [hdaudioB0D0], device 0: HDAudio Analog (*) []
>> card 1: hdaudioB0D2 [hdaudioB0D2], device 0: HDMI1 (*) []
>> card 1: hdaudioB0D2 [hdaudioB0D2], device 1: HDMI2 (*) []
>> card 1: hdaudioB0D2 [hdaudioB0D2], device 2: HDMI3 (*) []
>>
>> It is done by skipping back end devices and only counting front end
>> ones.
>>
>> Now there are few concerns I have:
>> - while rtd->id is not used much, few drivers seem to be using it as
>>     index into a table, above may break this use (although
>>     "include/sound/simple_card_utils.h: * the ID stored in rtd->id may not be a valid array index."
>>     suggests that maybe it is a bad idea anyway, but I'm not sure how
>>     generic that comment is)
>> - this will break user scripts, with hardcoded device IDs
>> - this will also break some UCMs with hardcoded IDs
>>
>> Now my main question is, if such patch would even be considered?
>> Perhaps device IDs are not considered as "stable" interface and can be
>> changed and my above worries are unnecessary.
>>
>> Patch is a result of discussion from:
>> https://github.com/alsa-project/alsa-ucm-conf/pull/499
>> and as such I may consider others ways of fixing the problem.
> 
> And it should've been RFC in topic... :( Sorry about that.

Looking to UCM configs, most of ASoC cards have PCM devices starting from 
zero. So this id is not used for all ASoC cards.

Also, a bit off-topic, but the driver name (hdaudioB?D?) for this particular 
driver should be corrected, too. It should be like 'hda-avs-dsp' or so. If I 
am not wrong, the SST driver name was 'hda-dsp'.

					Jaroslav

-- 
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.