[LAU] Pops and clicks but no xruns

[Paul Davis]

On Thu, 2007-04-05 at 02:00 -0400, Spencer Russell wrote:
> Recently I posted regarding nice low latencies on my brand-spankin-new
> Thinkpad R60. I was a bit premature though, because when I actually
> run any sound through jack I'm still getting lots of pops and clicks
> in my audio. I am not, however, getting any Xruns. I'm not sure what
> to look for as a culprit.
> 
> I already enabled "force 16 bit", which got rid of some nasty
> distortion, maybe something wacky with my IRQs? One of my worries is
> that the HDA card is on the same interrupt as my firewire and one of
> my USB drives. When I remove the modules though, leaving only HDA on
> its own interrupt, i still get the pops.
> 
> When I use audio without jack I get no clicks or pops, and changing
> jackd to capture only doesn't seem to help. I also boosted the
> priority of that interrupt thread with chrt --fifo --pid 99 `pidof
> 'IRQ 4'` without any change.
> 
> What could cause clicks without xruns? I'm baffled.

PCI bus hogging, for one thing. consider running a script like this
during system startup (mine is in /etc/rc.d/init.d/pcilatency). yours
would need adjusting to reflect the PCI IDs of the actual interfaces you
have installed.

#!/bin/sh

case $1 in
     start)
           # "open up" the PCI bus by allowing fairly long bursts for
all devices, increasing performance
           setpci -v -s "*:*.*" latency_timer=b0

           # maximise latency for RME Hammerfall, thus allowing
           # more data per PCI transfer and minimizing xfuns
           setpci -v -s 01:04.0 latency_timer=ff
           # ditto for the onboard AC97 audio interface
           setpci -v -s 00:07.5 latency_timer=ff
esac

exit 0