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author | Benjamin Tissoires <bentiss@kernel.org> | 2024-04-10 19:19:22 +0200 |
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committer | Benjamin Tissoires <bentiss@kernel.org> | 2024-05-07 15:38:53 +0200 |
commit | 04b3e5ab055553e074ea54ef316982b55cdde96b (patch) | |
tree | 48c4349295d9509c46a65491fd522189746c4d18 /drivers/hid/bpf/progs/README | |
parent | HID: do not assume HAT Switch logical max < 8 (diff) | |
download | linux-04b3e5ab055553e074ea54ef316982b55cdde96b.tar.gz linux-04b3e5ab055553e074ea54ef316982b55cdde96b.tar.bz2 linux-04b3e5ab055553e074ea54ef316982b55cdde96b.zip |
HID: bpf: add first in-tree HID-BPF fix for the XPPen Artist 24
This commit adds a fix for XPPen Artist 24 where the second button on
the pen is used as an eraser.
It's a "feature" from Microsoft, but it turns out that it's actually
painful for artists. So we ship here a HID-BPF program that turns this
second button into an actual button.
Note that the HID-BPF program is not directly loaded by the kernel itself
but by udev-hid-bpf[0]. But having the sources here allows us to also
integrate tests into tools/testing/selftests/hid to ensure the HID-BPF
program are actually tested.
[0] https://gitlab.freedesktop.org/libevdev/udev-hid-bpf
Link: https://lore.kernel.org/r/20240410-bpf_sources-v1-2-a8bf16033ef8@kernel.org
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Diffstat (limited to 'drivers/hid/bpf/progs/README')
-rw-r--r-- | drivers/hid/bpf/progs/README | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/drivers/hid/bpf/progs/README b/drivers/hid/bpf/progs/README new file mode 100644 index 000000000000..20b0928f385b --- /dev/null +++ b/drivers/hid/bpf/progs/README @@ -0,0 +1,102 @@ +# 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 +``` |