Updated Kamvas Pro 19 descriptor check

This fixes #43 (closed) for me, works a treat, and should also still work for the older firmware with the smaller descriptor.

To duplicate some info in that issue for context:

It seems newer firmware has a hid descriptor that is 438 bytes long, not the 328 the check is looking for, I don't know how to dump the firmware version on linux, but I suspect because my units hardware is newer that it's running an updated firmware.

Comparing against the hid recording in #36 (closed), it seems the following has been added:

#   0x05, 0x01,                    // Usage Page (Generic Desktop)              328
#   0x09, 0x01,                    // Usage (Pointer)                           330
#   0xa1, 0x01,                    // Collection (Application)                  332
#   0x09, 0x01,                    //   Usage (Pointer)                         334
#   0xa1, 0x00,                    //   Collection (Physical)                   336
#   0x05, 0x09,                    //     Usage Page (Button)                   338
#   0x19, 0x01,                    //     UsageMinimum (1)                      340
#   0x29, 0x03,                    //     UsageMaximum (3)                      342
#   0x15, 0x00,                    //     Logical Minimum (0)                   344
#   0x25, 0x01,                    //     Logical Maximum (1)                   346
# ┅ 0x85, 0x02,                    //     Report ID (2)                         348
#   0x95, 0x03,                    //     Report Count (3)                      350
#   0x75, 0x01,                    //     Report Size (1)                       352
# ┇ 0x81, 0x02,                    //     Input (Data,Var,Abs)                  354
#   0x95, 0x01,                    //     Report Count (1)                      356
#   0x75, 0x05,                    //     Report Size (5)                       358
# ┇ 0x81, 0x01,                    //     Input (Cnst,Arr,Abs)                  360
#   0x05, 0x01,                    //     Usage Page (Generic Desktop)          362
#   0x09, 0x30,                    //     Usage (X)                             364
#   0x09, 0x31,                    //     Usage (Y)                             366
#   0x15, 0x81,                    //     Logical Minimum (-127)                368
#   0x25, 0x7f,                    //     Logical Maximum (127)                 370
#   0x75, 0x08,                    //     Report Size (8)                       372
#   0x95, 0x02,                    //     Report Count (2)                      374
# ┇ 0x81, 0x06,                    //     Input (Data,Var,Rel)                  376
#   0x95, 0x04,                    //     Report Count (4)                      378
#   0x75, 0x08,                    //     Report Size (8)                       380
# ┇ 0x81, 0x01,                    //     Input (Cnst,Arr,Abs)                  382
#   0xc0,                          //   End Collection                          384
#   0xc0,                          // End Collection                            385
#   0x05, 0x0d,                    // Usage Page (Digitizers)                   386
#   0x09, 0x05,                    // Usage (Touch Pad)                         388
#   0xa1, 0x01,                    // Collection (Application)                  390
#   0x06, 0x00, 0xff,              //   Usage Page (Vendor Defined Page FF00)   392
#   0x09, 0x0c,                    //   Usage (Vendor Usage 0x0c)               395
#   0x15, 0x00,                    //   Logical Minimum (0)                     397
#   0x26, 0xff, 0x00,              //   Logical Maximum (255)                   399
#   0x75, 0x08,                    //   Report Size (8)                         402
#   0x95, 0x10,                    //   Report Count (16)                       404
# ┅ 0x85, 0x3f,                    //   Report ID (63)                          406
# ┇ 0x81, 0x22,                    //   Input (Data,Var,Abs,NoPref)             408
#   0xc0,                          // End Collection                            410
#   0x06, 0x00, 0xff,              // Usage Page (Vendor Defined Page FF00)     411
#   0x09, 0x0c,                    // Usage (Vendor Usage 0x0c)                 414
#   0xa1, 0x01,                    // Collection (Application)                  416
#   0x06, 0x00, 0xff,              //   Usage Page (Vendor Defined Page FF00)   418
#   0x09, 0x0c,                    //   Usage (Vendor Usage 0x0c)               421
#   0x15, 0x00,                    //   Logical Minimum (0)                     423
#   0x26, 0xff, 0x00,              //   Logical Maximum (255)                   425
# ┅ 0x85, 0x44,                    //   Report ID (68)                          428
#   0x75, 0x08,                    //   Report Size (8)                         430
#   0x96, 0x6b, 0x05,              //   Report Count (1387)                     432
# ┇ 0x81, 0x00,                    //   Input (Data,Arr,Abs)                    435
#   0xc0,                          // End Collection                            437

This PR updates the descriptor check to look for both the 328 and the 438 length descriptors, I'm not 100% sure the proper way to cross the probe boundary into the bpf machinery with the info needed, so i'm just using a bool, extended_descriptor which is used to control the memcpy size to truncate the descriptor if it's not the extended variant.

Anynyan, let me know if this looks decent or not~

Closes #43 (closed)

---

edit by @whot: add closes tag

changed the description

added 1 commit

• f82ab2b7 - Added updated Kamvas Pro 19 descriptor

Compare with previous version

mentioned in issue #43 (closed)

changed the description

I don't know how to dump the firmware version on linux, but I suspect because my units hardware is newer that it's running an updated firmware.

If you run huion-switcher from here it'll print the firmware version including the date - which you could then use via the HUION_FIRMWARE_ID udev property (see the keydial kd20 sources for example).

Thanks, overall this looks good with a few changes needed It'd especially be great if we could add the firmware versions as comments to make it easier to identify it for others.

Hey,

Yeah I'll try to do the fixups when I get a chance, I'm a little busy the next few days but I should be able to get to it around Wed if that's okay.

changed the description

added 1 commit

• 2e275937 - Added updated Kamvas Pro 19 descriptor

Compare with previous version

Couple of nitpicks, but otherwise looks good.

There is one missing bit that we didn't foresee, in terms of process: you are directly touching the stable file, which is probably not the best stable way to do things (considering that the first attempt was bogus for the old device is even more a hint that this is not correct).

So I think we should:

• first copy the stable file into testing (and amend meson.build)
• then add your commit on top (with my nitpicks)
• then let the magic happen and I can forward this to the kernel, which will eventually send back those changes into stable.

If you agree, I can easily do those changes myself in your branch (this will still keep you as the author both here and in the kernel)

approved this merge request

added 3 commits

• fb644904 - 1 commit from branch libevdev:main
• 08c09df3 - bpf: bump Huion Kamvas Pro 19 into testing
• 617a4d34 - Added updated Kamvas Pro 19 descriptor

Compare with previous version

marked this merge request as ready

resolved all threads

merged

mentioned in commit bentiss/hid@531a1cc6