[alsa-devel] [PATCH 1/3] add API to allow disabling period interrupts

Jaroslav Kysela perex at perex.cz
Mon May 17 18:22:11 CEST 2010

On Mon, 17 May 2010, pl bossart wrote:

>> 2) The avail_min parameter in sw_params was overlooked. The lowlevel
>>   drivers can use this value to compute the wake-up point and set hw
>>   appropriately, to do wake-up at requested time. We can add a support
>>   functions like "return how many samples are expected to be transferred
>>   for next wake-up point" to linux/sound/pcm.h. In case when this value
>>   is high, no interrupts (wake ups) will be processed in the driver. If
>>   hardware cannot do the precise transfers, we can program a system
>>   timer as the wake-up source.
> Isn't the interrupt-related behavior defined when you setup the DMA
> linked list. i.e when hw_params are frozen? The problem with sw_params
> is that they can change at any time, and the hardware may not support
> this. I have no idea how you would modify the HDAudio controller
> behavior dynamically for example.

Look my last sentence - we should use another timing source like system 
timer in this case.


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

More information about the Alsa-devel mailing list