[alsa-devel] [alsa-lib][RFC PATCH] ucm: reset config id of condition items

[Jaroslav Kysela]

Dne 23. 04. 20 v 15:06 Pierre-Louis Bossart napsal(a):
> 
> 
> On 4/22/20 8:58 PM, libin.yang at linux.intel.com wrote:
>> From: Libin Yang <libin.yang at intel.com>
>>
>> UCMv2 supports "If" statement and will merge the same items with
>> compound_merge(). If the items have the same id, it will fail to
>> add the config items. And the id of the item in an array is
>> automatically generated with the increased number. It is probably
>> that some items to be merged have the same id. Let's add prefix
>> in the id to avoid such situation.
>>
>> For example:
>>
>> If.seq1 {
>> 	Condition {
>> 		Type ControlExists
>> 		Control "name='PGA1.0 1 Master Playback Volume'"
>> 	}
>> 	True {
>> 		EnableSequence [
>> 			cset "name='PGA1.0 1 Master Playback Volume' 50"
>> 		]
>> 	}
>> }
>>
>> If.seq2 {
>> 	Condition {
>> 		Type ControlExists
>> 		Control "name='PGA2.0 2 Master Playback Volume'"
>> 	}
>> 	True {
>> 		EnableSequence [
>> 			cset "name='PGA2.0 2 Master Playback Volume' 50"
>> 		]
>> 	}
>> }
>>
>> If.seq3 {
>> 	Condition {
>> 		Type ControlExists
>> 		Control "name='PGA3.0 3 Master Playback Volume'"
>> 	}
>> 	True {
>> 		EnableSequence [
>> 			cset "name='PGA3.0 3 Master Playback Volume' 50"
>> 		]
>> 	}
>> }
>>
>> If seq1, seq2 and seq3 conditions are true, UCM will fail to initialize.
>>
>> This patch rename the config id to avoid the same id conflict.
> 
> The example confuses me completely, I checked three times and the seq1,
> seq2 and seq3 parts configure different controls.
> 
> Can you clarify what the conflict is and what id you were referring to?

The arrays in the ALSA configs are represented like:

User syntax:

name [
   value0
   value1
]

Internal tree:

name.0 value0
name.1 value1

or

name {
   0 value0
   1 value1
}

(all three syntaxes are equal, the array just removes the indexes for the 
readability)

This patch tries to change name.0 to something like name.unique-0 or so which 
is not so much pretty.

You can just declare the new sequences like this to avoid clash:

EnableSequence.seq3.cset "name='PGA3.0 3 Master Playback Volume' 50"

					Jaroslav

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