[systemd-devel] [PATCH udev v5] udev: Add builtin/rule to export evdev information as udev properties

David Herrmann dh.herrmann at gmail.com
Thu Jan 15 05:16:47 PST 2015


On Mon, Jan 12, 2015 at 5:52 AM, Zbigniew Jędrzejewski-Szmek
<zbyszek at in.waw.pl> wrote:
> On Sun, Jan 11, 2015 at 08:47:19PM +0100, Carlos Garnacho wrote:
>> This rule is only run on tablet/touchscreen devices, and extracts their size
>> in millimeters, as it can be found out through their struct input_absinfo.
>> The first usecase is exporting device size from tablets/touchscreens. This
>> may be useful to separate policy and application at the time of mapping
>> these devices to the available outputs in windowing environments that don't
>> offer that information as readily (eg. Wayland). This way the compositor can
>> stay deterministic, and the mix-and-match heuristics are performed outside.
>> Conceivably, size/resolution information can be changed through EVIOCSABS
>> anywhere else, but we're only interested in values prior to any calibration,
>> this rule is thus only run on "add", and no tracking of changes is performed.
>> This should only remain a problem if calibration were automatically applied
>> by an earlier udev rule (read: don't).
>>   v2: Folded rationale into commit log, made a builtin, set properties
>>       on device nodes themselves
>>   v3: Use inline function instead of macro for mm. size calculation,
>>       use DECIMAL_STR_MAX, other code style issues
>>   v4: Made rule more selective
>>   v5: Minor style issues, renamed to a more generic builtin, refined
>>       rule further.
> Applied.

After some more discussion (sorry for being late), I now merged it
into input_id. You can now run input_id on any input sysfs path and it
will do the right thing.


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