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HID: bpf: Add Huion Inspiroy Frego M button quirk

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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>
This commit is contained in:
Nikhil Chatterjee 2026-04-25 20:18:19 -07:00 committed by Benjamin Tissoires
parent 08918b98b0
commit 857e71cb0a
1 changed files with 87 additions and 0 deletions
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87
drivers/hid/bpf/progs/Huion__Inspiroy-Frego-M.bpf.c Normal file
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// SPDX-License-Identifier: GPL-2.0-only
#include "vmlinux.h"
#include "hid_bpf.h"
#include "hid_bpf_helpers.h"
#include <bpf/bpf_tracing.h>
/*
* Huion Inspiroy Frego M Pen Tablet
* Model L610
* 256c:8251 (Bluetooth)
* 256c:2012 (USB)
*/
#define VID_HUION 0x256C
#define PID_INSPIROY_FREGO_M 0x8251
#define PID_L610 0x2012
#define PEN_RDESC_SIZE 125
#define SECONDARY_SWITCH_OFFSET 17
HID_BPF_CONFIG(
HID_DEVICE(BUS_BLUETOOTH, HID_GROUP_GENERIC, VID_HUION, PID_INSPIROY_FREGO_M),
HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_HUION, PID_L610)
);
/*
* The pen descriptor reports the second side button as Secondary Tip Switch
* instead of Secondary Barrel Switch.
*
* Relevant part of the original pen report descriptor:
*
* 0x09, 0x42, // Usage (Tip Switch) 12
* 0x09, 0x44, // Usage (Barrel Switch) 14
* 0x09, 0x43, // Usage (Secondary Tip Switch) 16 <- change to 0x5a
* 0x09, 0x3c, // Usage (Invert) 18
* 0x09, 0x45, // Usage (Eraser) 20
* 0x15, 0x00, // Logical Minimum (0) 22
* 0x25, 0x01, // Logical Maximum (1) 24
*/
SEC(HID_BPF_RDESC_FIXUP)
int BPF_PROG(fix_secondary_barrel_rdesc, struct hid_bpf_ctx *hctx)
{
__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, HID_MAX_DESCRIPTOR_SIZE /* size */);
if (!data)
return 0; /* EPERM check */
if (hctx->size != PEN_RDESC_SIZE)
return 0;
if (data[0] != 0x05 || data[1] != 0x0d || /* Usage Page (Digitizers) */
data[2] != 0x09 || data[3] != 0x02 || /* Usage (Pen) */
data[16] != 0x09 ||
data[SECONDARY_SWITCH_OFFSET] != 0x43) /* Secondary Tip Switch */
return 0;
data[SECONDARY_SWITCH_OFFSET] = 0x5a;
return 0;
}
HID_BPF_OPS(fix_secondary_barrel) = {
.hid_rdesc_fixup = (void *)fix_secondary_barrel_rdesc,
};
SEC("syscall")
int probe(struct hid_bpf_probe_args *ctx)
{
ctx->retval = ctx->rdesc_size != PEN_RDESC_SIZE;
if (ctx->retval) {
ctx->retval = -EINVAL;
return 0;
}
if (ctx->rdesc[0] != 0x05 || ctx->rdesc[1] != 0x0d || /* Usage Page (Digitizers) */
ctx->rdesc[2] != 0x09 || ctx->rdesc[3] != 0x02 || /* Usage (Pen) */
ctx->rdesc[16] != 0x09 ||
ctx->rdesc[SECONDARY_SWITCH_OFFSET] != 0x43) { /* Secondary Tip Switch */
ctx->retval = -EINVAL;
return 0;
}
ctx->retval = 0;
return 0;
}
char _license[] SEC("license") = "GPL";