How to configure Ubuntu 11.10 for using 2 RME PCI Hammerfall DSP MADI cards together

The objective is to be able to use the 2 RME cards as one single 128 channel sound card. Ubuntu 11.10 does not detect the RME HDSPM out of the box, so we need to compile a new vanilla linux kernel obtained from git. It is also a good idea to make a small detour from the instructions below and configure the kernel for low-latency, but I will leave that for the brave souls (although it’s easy).

git clone https://github.com/tiwai/sound
cd sound
cp /boot/config-`uname -r` .config
yes '' | make oldconfig
sed -rie 's/echo "+"/#echo "+"/' scripts/setlocalversion
make-kpkg clean
CONCURRENCY_LEVEL=`getconf _NPROCESSORS_ONLN` fakeroot make-kpkg --initrd --append-to-version=-custom kernel_image kernel_headers
sudo dpkg -i linux-image-3.3.0-rc1-custom_3.3.0-rc1-custom-10.00.Custom_amd64.deb 
sudo dpkg -i linux-headers-3.3.0-rc1-custom_3.3.0-rc1-custom-10.00.Custom_amd64.deb
sudo update-initramfs -ck 3.3.0-rc1-custom
sudo update-grub

Reboot and you should be running the new kernel which should detect the cards. Doing

cat /proc/asound/cards

should list the cards.

Next we need to make sure we can name the cards individually since hw:0 will possible refer a different card after every reboot. To do this we place the following inside /etc/modprobe.d/hdspm.conf:

options snd_hdspm id=foo,bar

To merge the two sound cards into one for ALSA we create a ~/.asoundrc.

In our case we have the hdspms connected to RME’s ADI-648 units via optical madi cables. One of the ADI’s is the wordclock master for the the other ADI-648 and the pci cards, so we need to set the clock source and the inputs source:

amixer -c foo set 'System Clock Mode' 'AutoSync' && amixer -c bar set 'System Clock Mode' 'AutoSync'
amixer -c foo set 'Input Select' 'optical' && amixer -c bar set 'Input Select' 'optical'

Now we unmute the cards:

for i in `seq 1 64`; do amixer -c foo set 'Chn',$i 64 && amixer -c bar set 'Chn',$i 64; done

To get rid of xruns jack should run with realtime priorities (change johndoe to your user name):

dpkg-reconfigure -p high jackd
usermod -a -G audio johndoe

You can check your privileges with:

ulimit -r -l

You can now start jackd for the 128 channels sound card

jackd -R -P 70 -d alsa -r44100 -dmergedcards -p128 -o128 -i128

and have fun !

Thanks to Adrian Knoth and Florian Faber for all the help with the hdspm driver !

It took me about 2 months to compile this information, so I hope this is useful to someone.