[alsa-devel] Device creation order
perex at perex.cz
Fri Apr 3 09:50:47 CEST 2009
On Fri, 3 Apr 2009, Clemens Ladisch wrote:
> 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
> This is only true for drivers that load firmware with a hwdep device
> instead of using request_firmware(). Is there any driver that has not
> yet been converted? *grep* ... except usx2y?
>> - 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.
> The current implementation of the ALSA framework guarantees that the
> control device file is that latest one to be created for all the devices
> created at initialization. Any devices created later depend on some
> userspace action, so a small timeout won't help in this case.
The timeout might help to let alsactl utility to initialize the
soundcard's mixer. But I agree that alsactl should send a HAL message that
initial setting was done instead.
Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.
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