On Mon, 17 May 2010, pl bossart wrote:
- 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
----- Jaroslav Kysela perex@perex.cz Linux Kernel Sound Maintainer ALSA Project, Red Hat, Inc.