[alsa-devel] Device creation order

Daniel Mack daniel at caiaq.de
Fri Apr 3 09:40:09 CEST 2009

On Fri, Apr 03, 2009 at 09:31:40AM +0200, Jaroslav Kysela wrote:
>>> Unfortunately, driver may use more complex scenarios like:
>>> - some hardware requires additional firmware - in this case devices
>>>    might be created, but they are not useable until firmware is loaded
>>> - dynamic device creation at runtime - for example we have an
>>>    experimental HDA driver configuration code which might change
>>>    the arrangement of PCM devices on request from the user space
>>> I would suggest to wait awhile with some small timeout (0.5 sec?) for all
>>> devices to get the usual static arrangement working and handle extra
>>> dynamic cases, too.
>> Wouldn't the real fix be to make sure that the event from hal/udev
>> happens after all the initialization has finished, i.e. the device got
>> its firmware, all connected layers finished their work etc? Before all
>> that, the audio device is not really available, right?
> But even with this extension, the user space should handle dynamic device 
> reconfiguration (my second example case). The question is, if it makes  
> sense to handle group of devices per card basis or just take single  
> devices and dynamically handle device changes.

That's another issue IMO, which needs different attention. Signaling audio
devices being added (via udev) before it's actually usable is rather a bug
than a missing extension, wouldn't you say?


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