[alsa-devel] my udev rules are breaking my dmixer setup why?
Jelle de Jong
jelledejong at powercraft.nl
Wed Jul 29 12:44:37 CEST 2009
On 11/11/08 18:55, Jaroslav Kysela wrote:
> On Tue, 11 Nov 2008, Jelle de Jong wrote:
>
>> Jaroslav Kysela wrote:
>>> On Tue, 11 Nov 2008, Takashi Iwai wrote:
>>>
>>>>> Almost all devices can be managed with udev rules, that is where the
>>>>> system is designed for, there are also alsa rules in there, if they
>>>>> don't work what is wrong then? is it an alsa issue, or udev, what are
>>>>> the dependencies when alsa uses hardware. How are the /dev/snd/* devices
>>>>> used and what is the /proc/asound/* for ?
>>>> The card index mechanism in ALSA was introduced much before udev
>>>> was born. It's just a legacy mechanism, but it's hard to kill without
>>>> breaking the running system, unfortunately.
>>>
>>> Note that you can identify your card via the text identification (check
>>> /proc/asound/cards to get it in []). You can set this identification in
>>> the module insert time and use for example 'hw:Intel' in your apps without
>>> bothering with indexes.
>>>
>>> The missing part is the modification of this text identification using
>>> sysfs at runtime for udev. Some time ago, I was trying to add this setup
>>> to /sys/class/sound, but the sysfs core code was not prepared for this
>>> change. I'll try to check the situation again.
>>>
>>
>> As response to:
>> http://mailman.alsa-project.org/pipermail/alsa-devel/2008-November/012366.html
>>
>> I am not sure if it is good practice to repose to an RFC if so please
>> tell me then we will continue the discussion in the RFC thread.
>>
>> Thank you Jaroslav for creating the patch this is really appreciated, if
>> all things work I will send you some dutch stroopwafels :-D
>>
>> I am just curious how you patch can be used with udev? What did you have
>> in mind?
>>
>> Would something like this be possible:
>>
>> SUBSYSTEM=="sound", ACTION="add" KERNELS=="3-1",
>> NAME="snd/by-id/audiodevice0"
>> SUBSYSTEM=="sound", ACTION="add" KERNELS=="3-2",
>> NAME="snd/by-id/audiodevice1"
>
> No, something like this:
>
> SUBSYSTEM=="sound", ACTION=="add", KERNEL=="controlC*", KERNELS=="3-2", \
> ATTR{device/id}="audiodevice1"
>
>> pcm.!default {
>> type plug
>> slave.pcm dmixer
>> }
>> pcm.dmixer {
>> type dmix
>> ipc_key 1024
>> slave.pcm hw:audiodevice0
>> }
>
> This looks OK.
>
> Jaroslav
>
Hello everybody,
It has been a while and I have been waiting until the patch made it into
Debian and now it finally has, so I started testing and it seems to work
that the patch works and I am very grateful for it.
I still have list of issues, but I will make new treads for them now.
Thanks again,
Best regards,
Jelle de Jong
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