How to change CSL Loadcell Brake Pressure?

[TheLCraft]

I am on Cachy OS and have a CSL Loadcell Brake Pedal connected via USB to the PC. The rest of my Setup is Moza so I don't have an option to change settings on the wheel. The problem is that my Brake Pressure always reverts to 20% when I want it to be at 70-75%. I can change it on windows but even then it reverts back to 20% when I log into Linux. I tried writing the load file but I'm not able to do so and only get:
An error occurred while redirecting file '/sys/module/hid_fanatec/drivers/hid:fanatec/0003:0EB7:6205.0002/load'
open: Permission denied
When I try to write with root permissions, I don't get this warning but also nothing changes. Do you have some ideas on what to do?

[gotzl]

Hi, the driver sets a default value for the load once the module loads. This default can be changed with s.t. like that (untested):

echo "options hid_fanatec init_load=5" | tee /etc/modprobe.d/hid_fanatec.conf

The permission denied error could be because you're not in the games group (or because the udev rules did not run at all). Could you checkout the output of the groups command and see if it includes games?

Now, why it doesn't change when you're writing with root, I don't understand yet.. Could you check dmesg after attempting to write? Also note, that the value has to be between 0 and 10 ..

[dinuxlt]

for dmesg you need to use sudo
sudo dmesg

[TheLCraft]

Id did log in again after adding myself to the group. When I type in the command, I get
❯ ls -l /sys/module/hid_fanatec/drivers/hid:fanatec/0003:0EB7:6205.0002/
lrwxrwxrwx - root 14 Nov 20:30  driver -> ../../../../../../../bus/hid/drivers/fanatec
lrwxrwxrwx - root 14 Nov 20:30  firmware_node -> ../../../../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:4c/device:4d/device:55
drwxr-xr-x - root 14 Nov 20:30  hidraw
drwxr-xr-x - root 14 Nov 20:30  input
drwxr-xr-x - root 14 Nov 20:30  physical_location
drwxr-xr-x - root 14 Nov 20:30  power
lrwxrwxrwx - root 14 Nov 20:30  subsystem -> ../../../../../../../bus/hid
.r--r--r-- 4,1k root 14 Nov 20:30 󰡯 country
.rw-rw-r-- 4,1k root 14 Nov 20:30 󰡯 load
.r--r--r-- 4,1k root 14 Nov 20:30 󰡯 modalias
.r--r--r-- 4,1k root 14 Nov 20:30 󰡯 report_descriptor
.rw-r--r-- 4,1k root 14 Nov 20:30 󰡯 uevent

[gotzl]

Hmm, looks abit strange to me, but ok, let's do one thing after another...
First, try

echo 'file hid-ftec*.c +p' | sudo tee /proc/dynamic_debug/control
echo 8 | sudo tee /sys/module/hid_fanatec/drivers/hid:fanatec/0003:0EB7:6205.0003/load
sudo dmesg | tail

and post the output, it should say s.t. like [99682.331898] hid-ftec.c: ... set_load 08. If this is the case, then I would expect that the required brake pressure should be way higher than before.

[TheLCraft]

I actually found a solution, it's a bit weird but it works. With

echo N | sudo tee /sys/module/hid_fanatec/drivers/hid:fanatec/0003:0EB7:6205.0003/load

I can change the brake pressure momentarily till the next restart, with N beeing the brake pressure divided by 5 (so 70% would be N=14, 40% is N=8, ...).

With

echo "options hid_fanatec init_load=N" | tee /etc/modprobe.d/hid_fanatec.conf

I can change the default value, which isn't affected by restarts.

However I am not able to see what value is actually set in Linux since in the Load File it is most of the time just 0 and sometimes randomly any value like 19 or 238, so this probably doesn't say anything. But whenever I log into windows after applying one of the two commands above I can see that it worked as it should and when I go into a game I can clearly see that something changed.

Thanks for your help!

[gotzl]

Reading back the value wasn't implemented as hinted in the readme. I've fixed that now with 0e6510b and reading from the file should now yield the correct value.