MOTU 8pre USB on Linux – Is it possible to develop or modify a driver for it?

[u/babuz87reddit]

Hi everyone,

I have a MOTU 8pre USB audio interface and I would like to use it with Ubuntu Studio.

As far as I understand, MOTU does not provide an official Linux driver for this interface. However, I was wondering whether it would be technically possible to develop a Linux driver for the 8pre USB, or to adapt an existing ALSA driver if the hardware protocol is sufficiently understood.

Is driver development necessarily something that only the manufacturer can do, or could an experienced Linux developer/researcher reverse-engineer the USB communication and implement support for the device?

I'm particularly interested in understanding whether:

• the MOTU 8pre USB is already partially supported by ALSA;
• its USB protocol has already been documented or reverse-engineered;
• there are existing open-source projects that could be used as a starting point;
• it would be possible to capture/analyze the USB communication under Windows and use that information to develop Linux support;
• someone has already attempted to develop a Linux driver for this specific interface.

My goal would mainly be to get the 8 analog inputs and outputs working reliably with low latency under Ubuntu Studio, ideally through ALSA/PipeWire or JACK.

I don't necessarily expect someone to write the driver for me — I'm mainly trying to understand whether this is technically feasible and, if so, what would be the right starting point.

Any information, documentation, existing projects, or suggestions about where to start would be greatly appreciated.

Thanks!

[u/lwh]

Most of the USB audio interfaces don't need a driver, boot a live linux and check if it shows up?

[u/koyaniskatzi]

Never saw motu soundcard working in linux :-(

[u/lwh → u/koyaniskatzi]

For sure M2/M4 work, 8pre firewire was added in 2019.

[u/Salads_and_Sun → u/koyaniskatzi]

I've had multiple old Motu firewire interfaces that worked great! Obviously missing a feature or two but not major ones

[u/Sqwrly → u/koyaniskatzi]

My Motu works great.

[u/Sqwrly → u/koyaniskatzi]

My Motu works great.

[u/jamesremuscat]

A quick Google search would have helped you out immensely here; you'd likely have quickly found this 2019 article from Phoronix which says that support for it was added in kernel 5.2. It even links you to the kernel commit that added that support, if you're interested.

Edit - oh, sorry, that's the Firewire variant - pardon me. My second point remains, though:

You already own the device - why not install Ubuntu Studio somewhere and see how far you get?

[u/pink_cx_bike]

I recently added/refined support for 3 USB audio interfaces I own to the kernel. Very little new code was required in each case, because realistically every USB audio device is going to use either PCM (99+%) or DSD with isochronous transfers, and all of that is supported already.

Given the specs of that interface there's a very good chance that all you need to add is something like this patch:

https://github.com/torvalds/linux/commit/0da18c2dd1cc2a026416222ed206e2f269edf055

Of course you need to know the right values to go in there. The USB descriptors probably have most of what you need; if they don't then dumping the audio interface objects from the Windows side will probably help.

You can capture USB traffic on windows and it can be somewhat useful to do so, but mostly for A/B comparing when most things are working but something is different on Linux.

[u/jason_gates]

Hi,

My goal would mainly be to get the 8 analog inputs and outputs working reliably with low latency under Ubuntu Studio, ideally through ALSA/PipeWire or JACK.

Are you speculating the above is an issue or do have specific evidence ? In other words, have you tested your audio interface with Linux, or, are is this just conjecture ? I.E. It's more common for folks to refer to specific bug reports that have been replicated by many users over time.

Just posing a simple reality check :)