RFT: implementation of MOTU FireWire series CueMix DSP and CueMix FX

Hi all,

After investigation for protocols of MOTU FireWire series including features of CueMix DSP and CueMix FX, I've written implementation corresponding to the features in snd-firewire-ctl-services project[1]. If you are enough interested in it, would you please test the implementation?

The first aim of this test request is to check whether the protocol implementation works as well out of my development environment.

# Disclaimer

* The aim of the work is to reveal relevant protocols so adequately and write the implementation. It is out of my scope to produce user-friendly applications such as GUI with cool user-delighted look and feel. (This is also the reason that the message is so long for general users.)

# Acknowledgment

When I made investigation plan for the protocols and evaluated the result of investigation, documents included in ffado source code[13] is helpful. The documentation includes a part of the result, while some parts are newly revealed in this time. I appreciate for document writers.

# Current status

* Below models are supported and I tested * 828 * 896 * 828mk2 * 896hd * 8 pre * Ultralite * 4 pre * Audio Express * 828mk3 (FireWire only/Hybrid) * Ultralite mk3 (FireWire only/Hybrid) * The most of control functions are available via ALSA control interface * Hardware metering support * Interaction support between on-board control component such as knob, utilizing notification mechanism of ALSA control interface

# Requirements

For the test, you need to solve long list of requirements since the protocol implementation is new and lays down user space as well as kernel space. I'm sorry for testers to discourage your motivation, but they are required...

* Linux kernel v5.13 or later * a commit 66c6d1ef86ff ('ALSA: control: Add memory consumption limit to user controls')[2] is required since many user-defined control element sets are used. * Installation of backport codes for ALSA firewire stack * They comes from Linux kernel v5.16 prepatch (not released yet). * Please follow to instructions in my remote repository[3] * Installation of alsa-gobject v0.2.1 or later. * alsa-gobject project[4] provides libraries which perform as glue for several kind of language bindings to use UAPI of Linux sound subsystem. For detail, please refer to release announcement[5]. * Installation of libhinawa topic branch * libhinawa project[6] also provides library as glue for UAPI of ALSA firewire stack. * The topic branch (topic/motu-mixer-ioctl)[7] includes new APIs to use functions added in the kernel v5.16 prepatch. * Rust v1.51 or later * I use Rust programming language for the protocol implementation in user space side. * Build topic branch of snd-firewire-ctl-services * snd-firewire-ctl-services project[8] includes the series of implementation for protocols specific to ASICs/Vendors/Models. Additionally, as reference of service programs, it includes runtime implementation based on ALSA control interface and ALSA Sequencer interface. * The topic branch ('topic/motu-mixer-ioctl') includes implementation for the test.

# Test procedure

When the above requirements are satisfied, the service program can be build by below command line. It takes a bit long than compiling with C language since Rust compiler does more work than C (mainly due to type inference and lifetime check for safe runtime).

$ cargo build -p snd-firewire-ctl-services

The service program for MOTU FireWire series runs by below command line:

$ cargo run --bin snd-firewire-motu-ctl-service CARD_ID

The CARD_ID is the numeric ID of sound card corresponding to your device. You need to load ALSA firewire-motu driver in advance:

$ sudo modprobe snd-firewire-motu $ cat /proc/asound/cards ... 2 [UltraLiteMk3 ]: FW-MOTU - UltraLiteMk3 MOTU UltraLiteMk3 (version:100800), GUID ...

In the above example, CARD_ID should be 2.

When the service program runs, you can see control elements via ALSA control interface. You can operate them by usual tools of ALSA control application, but I prefer 'qashctl' in 'qastools' project[11].

Due to specification of protocols defined by MOTU, notifications from the device for some controls are firstly available when isochronous packets are transmitted by the device. Please run any of ALSA PCM applications when testing.

The aim of the request is whether the service program can be built and run out of my development environment. So I don't expect you so much. However, If you are interested, please check the other parts about which I concern:

* The range of value for each control is valid or not. * Inverse evaluation of each control with boolean value. * The lack of control which should be produced by the service program.

# Filing issues

* Please use issue service in github.com[10]. * Preferable issues * The service program aborts when I operate control A. * The service program doesn't interact with on-board operation B. * The service program looks to be frozen when I operate C. * The behaviour of control element D is odd. * Unexpected issues * Why device A is not supported * It's preferable for you to take your time to cooperate with me if you wish. It might take a long time since the implementation lays down user space and kernel space. * If so, please file the issue to my remote repository for kernel prepatch[12]. * Why we have no GUI with cool look and feel * It's your work. The GUI application might be an ALSA control application which interacts with the service program. * I can not get which control value corresponds to actual ports * It is restriction under current design of ALSA control interface. We need to work for any extension to the design. * The name of control B is not user-friendly. * The name of controls are not fixed yet since we have few name convention for controls in studio-use equipments. It might corresponds to discussion in ALSA upstream. In my opinion, Linux audio developers have been enough lazy to the issue for recent decade.

[1] https://github.com/alsa-project/snd-firewire-ctl-services/ [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... [3] https://github.com/takaswie/snd-firewire-improve [4] https://github.com/alsa-project/alsa-gobject/ [5] https://lore.kernel.org/alsa-devel/20200623093239.GA68404@workstation/ [6[ https://github.com/alsa-project/libhinawa [7] https://github.com/alsa-project/libhinawa/tree/topic/motu-mixer-ioctl [8] https://github.com/alsa-project/snd-firewire-ctl-services/ [9] https://github.com/alsa-project/snd-firewire-ctl-services/tree/topic/motu-mi... [10] https://github.com/alsa-project/snd-firewire-ctl-services/issues [11] https://gitlab.com/sebholt/qastools [12] https://github.com/takaswie/snd-firewire-improve/issues [13] https://web.archive.org/web/20110704073441/http://subversion.ffado.org/brows...

Cheers

Takashi Sakamoto