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Nikhil ChatterjeeandBenjamin Tissoires
857e71cb0a
The Huion Inspiroy Frego M pen report descriptor exposes the second side button as Secondary Tip Switch instead of Secondary Barrel Switch. This makes userspace see the control as the wrong pen button. Add a HID-BPF report descriptor fixup for the Bluetooth 256c:8251 device and USB 256c:2012 L610 variant. The fixup matches the expected pen descriptor and rewrites the offending usage from Secondary Tip Switch to Secondary Barrel Switch. Tested by building the HID-BPF object with: make -C drivers/hid/bpf/progs Huion__Inspiroy-Frego-M.bpf.o Signed-off-by: Nikhil Chatterjee <nikhilc1527@gmail.com> Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
# HID-BPF programs
This directory contains various fixes for devices. They add new features or
fix some behaviors without being entirely mandatory. It is better to load them
when you have such a device, but they should not be a requirement for a device
to be working during the boot stage.
The .bpf.c files provided here are not automatically compiled in the kernel.
They should be loaded in the kernel by `udev-hid-bpf`:
https://gitlab.freedesktop.org/libevdev/udev-hid-bpf
The main reasons for these fixes to be here is to have a central place to
"upstream" them, but also this way we can test them thanks to the HID
selftests.
Once a .bpf.c file is accepted here, it is duplicated in `udev-hid-bpf`
in the `src/bpf/stable` directory, and distributions are encouraged to
only ship those bpf objects. So adding a file here should eventually
land in distributions when they update `udev-hid-bpf`
## Compilation
Just run `make`
## Installation
### Automated way
Just run `sudo udev-hid-bpf install ./my-awesome-fix.bpf.o`
### Manual way
- copy the `.bpf.o` you want in `/etc/udev-hid-bpf/`
- create a new udev rule to automatically load it
The following should do the trick (assuming udev-hid-bpf is available in
/usr/bin):
```
$> cp xppen-ArtistPro16Gen2.bpf.o /etc/udev-hid-bpf/
$> udev-hid-bpf inspect xppen-ArtistPro16Gen2.bpf.o
[
{
"name": "xppen-ArtistPro16Gen2.bpf.o",
"devices": [
{
"bus": "0x0003",
"group": "0x0001",
"vid": "0x28BD",
"pid": "0x095A"
},
{
"bus": "0x0003",
"group": "0x0001",
"vid": "0x28BD",
"pid": "0x095B"
}
],
...
$> cat <EOF > /etc/udev/rules.d/99-load-hid-bpf-xppen-ArtistPro16Gen2.rules
ACTION!="add|remove", GOTO="hid_bpf_end"
SUBSYSTEM!="hid", GOTO="hid_bpf_end"
# xppen-ArtistPro16Gen2.bpf.o
ACTION=="add",ENV{MODALIAS}=="hid:b0003g0001v000028BDp0000095A", RUN{program}+="/usr/local/bin/udev-hid-bpf add $sys$devpath /etc/udev-hid-bpf/xppen-ArtistPro16Gen2.bpf.o"
ACTION=="remove",ENV{MODALIAS}=="hid:b0003g0001v000028BDp0000095A", RUN{program}+="/usr/local/bin/udev-hid-bpf remove $sys$devpath "
# xppen-ArtistPro16Gen2.bpf.o
ACTION=="add",ENV{MODALIAS}=="hid:b0003g0001v000028BDp0000095B", RUN{program}+="/usr/local/bin/udev-hid-bpf add $sys$devpath /etc/udev-hid-bpf/xppen-ArtistPro16Gen2.bpf.o"
ACTION=="remove",ENV{MODALIAS}=="hid:b0003g0001v000028BDp0000095B", RUN{program}+="/usr/local/bin/udev-hid-bpf remove $sys$devpath "
LABEL="hid_bpf_end"
EOF
$> udevadm control --reload
```
Then unplug and replug the device.
## Checks
### udev rule
You can check that the udev rule is correctly working by issuing
```
$> udevadm test /sys/bus/hid/devices/0003:28BD:095B*
...
run: '/usr/local/bin/udev-hid-bpf add /sys/devices/virtual/misc/uhid/0003:28BD:095B.0E57 /etc/udev-hid-bpf/xppen-ArtistPro16Gen2.bpf.o'
```
### program loaded
You can check that the program has been properly loaded with `bpftool`
```
$> bpftool prog
...
247: tracing name xppen_16_fix_eraser tag 18d389353ed2ef07 gpl
loaded_at 2024-03-28T16:02:28+0100 uid 0
xlated 120B jited 77B memlock 4096B
btf_id 487
```