Development
To actually try modifying the driver source code, and build your modification against your current running kernel, do this (don't worry - the outcome stays in this directory):
make -C /lib/modules/`uname -r`/build M=`pwd`/sound/usb clean
make -C /lib/modules/`uname -r`/build M=`pwd`/sound/usb modules
Untested Something like this would install the newly built modules in your system against your current kernel.
You might want to do make -n to see where the command put the modules:
make -C /lib/modules/`uname -r`/build M=`pwd`/sound/usb modules_install
The linux kernel prefers to load modules under /lib/modules/*/updates and /lib/modules/*/extra over elsewhere under /lib/modules/*,
so it is safer to manually copy new *.ko into those
directories, and run depmod -a to let the kernel rescan them, rather than doing make ... modules_install.
The v5.12-sound-master branch tracks the linux kernel sound maintainer Takashi's tree.
The v5.12-dev branch tracks Vladimir / sadko4u 's. The v5.12-scarlett-gen3 branch tracks Geoffrey
Bennett's scarlett-gen3 development. They can be accessed by the instructions below,
replacing v5.12-sound-master by v5.12-dev or v5.12-scarlett-gen3:
git clone -b v5.12-sound-master https://github.com/Focusrite-Scarlett-on-Linux/sound-usb-kernel-module.git
cd sound-usb-kernel-module
make -C /lib/modules/`uname -r`/build M=`pwd`/sound/usb clean
make -C /lib/modules/`uname -r`/build M=`pwd`/sound/usb modules
# copy all the *.ko from under sound/usb into /lib/modules/`uname -r`/updates ; see the README
depmod -a
depmod -v -a (with -v) gives rather verbose messages about kernel modules. You should find those new ones being
processed.
Also remember to create a /etc/modprobe.d/scarlett.conf with device_setup=1 option for the device as in the
detailed instruction, duplicated further below.
After reboot, if you run dmesg,
you should see Focusrite Scarlett Gen 2/3 Mixer Driver enabled [sadko4u mod] ... for one,
and Focusrite Scarlett Gen 2/3 Mixer Driver enabled v5.12.9s1 ...
for the other.
If your kernel has CONFIG_MMODULE_SIG_FORCE=y (most secure-boot distribution kernels are), you will need to have a pair of certs/signing_key.pem
and certs/signing_key.x509, acceptable to your current BIOS, to sign the kernel modules.
Add a single line #define DEBUG 1 to the top of sound/usb/mixer_scarlett_gen2.c, to enable some rather noisy debug messaging code, if needed.
Enabling new functionality at load time
You need to enable the driver at module load time with the device_setup=1 option to insmod/modprobe. Create a new file /etc/modprobe.d/scarlett.conf, with
the following one-line content:
Gen 2:
- 6i6:
options snd_usb_audio vid=0x1235 pid=0x8203 device_setup=1 - 18i8:
options snd_usb_audio vid=0x1235 pid=0x8204 device_setup=1 - 18i20:
options snd_usb_audio vid=0x1235 pid=0x8201 device_setup=1
Gen 3:
- Solo:
options snd_usb_audio vid=0x1235 pid=0x8211 device_setup=1 - 2i2:
options snd_usb_audio vid=0x1235 pid=0x8210 device_setup=1 - 4i4:
options snd_usb_audio vid=0x1235 pid=0x8212 device_setup=1 - 8i6:
options snd_usb_audio vid=0x1235 pid=0x8213 device_setup=1 - 18i8:
options snd_usb_audio vid=0x1235 pid=0x8214 device_setup=1 - 18i20:
options snd_usb_audio vid=0x1235 pid=0x8215 device_setup=1
Or you can use the sledgehammer: options snd_usb_audio device_setup=1,1,1,1 to pass that option to the first 4 USB audio devices.