On Fri, Apr 02, 2010 at 11:42:42AM +0100, Mark Brown wrote: > On Fri, Apr 02, 2010 at 11:53:58AM +0200, Sascha Hauer wrote: > > On Thu, Apr 01, 2010 at 06:01:38PM +0200, Valentin Longchamp wrote: > > > > The thing is that I get a less than a second sound loop (I use aplay to > > > test, so userspace app should be ok), as if the buffer that the fiq asm > > > interrupt (from ssi_fiq.S) copies to the SSI hardware never was updated. > > > > If I have understood the fiq behaviour correctly, you have a asm fiq > > > interrupt that does copy a larger tx buffer into the SSI hardware. > > > Besides it, you have the imx_ssi_timer_callback that checks when the tx > > > buffer was completely copied. If it is the case, then a new buffer tx > > > buffer is "issued" with the snd_pcm_period_elapsed call (and then > > > snd_pcm_update_hw_ptr0). Is this behaviour correct ? > > > Yes. > > What sample rate are you trying to play and what buffer size? In my > testing the FIQ was really struggling with most applications at sample > rates over ~16kHz since you need each audio period to be long enough to > at least fill the interval between timer polls but applications wanted > to select buffer sizes that were consumed faster than the timer tick. I just stumbled upon a board which had something in /etc/asound.conf which decreased the buffer sizes. The result was choppy sound and a cpu utilisation of ~40%. After deleting the file I could play sounds (and record simultaniously) with rates up to 44100kHz without visible cpu utilisation. Looking at it I realised that poll_time is 0, so the timer gets reloaded with the actual jiffies value which of course is a bad idea. We should probably use a hrtimer here. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
