Documentation/hid/hidintro.rst

1 .. SPDX-License-Identifier: GPL-2.0
8 descriptors are, and of how a casual (non-kernel) programmer can deal
18    hidreport-parsing
30 wheel; movement sensitivity differs between different models, and so
40 bits from 8 to 15 is the delta x coordinate of a mouse".
50 Documentation/hid/hid-transport.rst). Devices may misbehave because the
60    <https://www.usb.org/document-library/device-class-definition-hid-111>`_ (HID Spec from now on)
61  * the `HID Usage Tables <https://usb.org/document-library/hid-usage-tables-14>`_ (HUT from now on)
64 (USB, I2C, Bluetooth, etc.). See Documentation/hid/hid-transport.rst.
73   $ hexdump -C /sys/bus/hid/devices/0003\:093A\:2510.0002/report_descriptor
95 Documentation/hid/hidreport-parsing.rst; you only need to understand it
107   * `hid-tools <https://gitlab.freedesktop.org/libevdev/hid-tools>`_,
113 Parsing the mouse HID report descriptor with `hid-tools
114 <https://gitlab.freedesktop.org/libevdev/hid-tools>`_ leads to
117     $ ./hid-decode /sys/bus/hid/devices/0003\:093A\:2510.0002/report_descriptor
173     # 0x15, 0x81, 		     //	Logical Minimum (-127)  	   40
176 each of them can send values ranging from -127 up to including 127 ::
205 We can check the values sent by resorting e.g. to the `hid-recorder`
206 tool, from `hid-tools <https://gitlab.freedesktop.org/libevdev/hid-tools>`_:
209   $ sudo ./hid-recorder /dev/hidraw1
212   output of hid-decode
250 ---------------------------------
320 …02,        //   Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile)
350     os: "opensuse-tumbleweed:20230619"
351     kernel: "6.3.7-1-default"
354   - node: /dev/input/event1
387       - ID_INPUT=1
388       - ID_INPUT_MOUSE=1
389       - LIBINPUT_DEVICE_GROUP=3/3f0/94a:usb-0000:05:00.3-2
393     - evdev:
394       - [  0,	   0,	4,   4,      30] # EV_MSC / MSC_SCAN		     30 (obfuscated)
395       - [  0,	   0,	1, 272,       1] # EV_KEY / BTN_LEFT		      1
396       - [  0,	   0,	0,   0,       0] # ------------ SYN_REPORT (0) ---------- +0ms
397     - evdev:
398       - [  1, 207892,	4,   4,      30] # EV_MSC / MSC_SCAN		     30 (obfuscated)
399       - [  1, 207892,	1, 273,       1] # EV_KEY / BTN_RIGHT		      1
400       - [  1, 207892,	0,   0,       0] # ------------ SYN_REPORT (0) ---------- +1207ms
401     - evdev:
402       - [  2, 367823,	4,   4,      30] # EV_MSC / MSC_SCAN		     30 (obfuscated)
403       - [  2, 367823,	1, 272,       0] # EV_KEY / BTN_LEFT		      0
404       - [  2, 367823,	0,   0,       0] # ------------ SYN_REPORT (0) ---------- +1160ms
406     - evdev:
407       - [  3, 247617,	4,   4,      30] # EV_MSC / MSC_SCAN		     30 (obfuscated)
408       - [  3, 247617,	1, 273,       0] # EV_KEY / BTN_RIGHT		      0
409       - [  3, 247617,   0,   0,       0] # ------------ SYN_REPORT (0) ---------- +880ms
412 ``evemu-record``.
424     will not able to make sense of the HID report descriptor;
436 ------
439 knows how to fix - these are called the HID quirks and a list of those
444 `drivers/hid/hid-quirks.c`. How to do it should be relatively
449 .. kernel-doc:: include/linux/hid.h
454 hid-quirks.c and **be submitted upstream**.
455 See Documentation/process/submitting-patches.rst for guidelines on how
456 to submit a patch. Quirks for other busses need to go into hid-quirks.c.
459 -----------------------------
462 resort to eBPF, as described in Documentation/hid/hid-bpf.rst.
478 `drivers/hid/hid-aureal.c` or `drivers/hid/hid-samsung.c` for a slightly
481 Check Documentation/hid/hidreport-parsing.rst if you need any help
488 everyone else. See Documentation/process/submitting-patches.rst for
493 -----------------------------------------
502 ----------------------------
510   file `samples/hidraw/hid-example.c` for an example.
511   The output of ``hid-example`` would be, for the same mouse::
513     $ sudo ./hid-example
519     Raw Phys: usb-0000:05:00.4-2.3/input0