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Benjamin Tissoires d9ca1c990a Input: reserve 2 events code because of HID
Prior to commit 190d7f02ce ("HID: input: do not increment usages when
a duplicate is found") from the v4.18 kernel, HID used to shift the
event codes if a duplicate usage was found. This ended up in a situation
where a device would export a ton of ABS_MISC+n event codes, or a ton
of REL_MISC+n event codes.

This is now fixed, however userspace needs to detect those situation.
Fortunately, ABS_MT_SLOT-1 (ABS_MISC+6) was never assigned a code, and
so libinput can detect fake multitouch devices from genuine ones by
checking if ABS_MT_SLOT-1 is set.

Now that we have REL_WHEEL_HI_RES, libinput won't be able to differentiate
true high res mice from some other device in a pre-v4.18 kernel.

Set in stone that the ABS_MISC+6 and REL_MISC+1 are reserved and should not
be used so userspace can properly work around those old kernels.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2018-10-04 21:06:45 +02:00
Documentation Input: Add the `REL_WHEEL_HI_RES` event code 2018-09-05 10:12:07 +02:00
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README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.