[LAU] Intel-hda jack low latency howto

A intel-hda jack low latency howto (by wirelessdreamer) I've seen asked many times on the list how to get intel-hda cards working with low latency, in duplex operation. Here is a full, step by step, on how I got 4ms latency. I'm using a Dell M90 with a Quadro fx 1500, attached to a docking station with a Maudio Delta 66 pci card (secondary card) in it, the binary Nvidia drivers and Compiz. So if you were wondering, it is possible. :) 1. Kernel (i'm not going to walk you through how to compile a kernel) (the last kernel before the big kernel lock regression) * wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.24.7.tar.bz2 * tar xvjf linux-2.6.24.7.tar.bz2 * cd linux-2.6.24.7.tar.bz2 (if you don't see it here look in the projects/rt/older/ directory) * wget http://www.kernel.org/pub/linux/kernel/projects/rt/patch-2.6.24.7-rt21.bz2 * bzcat ../patch-2.6.24.7-rt21.bz2 * wget http://pastebin.com/pastebin.php?dl=f6ad31838 * mv pastebin.php\?dl\=f6ad31838 .config.old * make oldconfig (build and install your kernel) 2. Module Options Add the following line to the file your distribution has its module options in (in ubuntu it is /etc/modules.d/alsa-base) options snd-hda-intel model=ref position_fix=1 enable=1 index=0 3. Mixer Options (VERY IMPORTANT ! ! !) enable capture/record elements in mixer without this jack can't play nicely with intel-hda cards 4. RT Permissions In most modern distros /etc/security/limits.conf is where realtime permissions are set, I added these 3 lines to it, and added myself to the @audio group in /etc/group @audio - memlock 1024000 @audio - nice -10 @audio - rtprio 99 5. Jack options I use qjackctl to set these put a check in Realtime Priority 89 Frames/Period 64 Sample Rate 48000 Periods/Buffer 3