We use the unofficial, Windows 8, Relative Scan time HID usage
(Digitizer page, 0x56) to add timestamps to our HID touchpad
events.
The timestamps is a rolling, unsigned, 16-bit integer, with a
resolution of 100us (so it wraps around every 6.5s).
The host will be able to synchronize to that timestamp, resetting
an offset every time the touchpad is quiet a certain amount of
time (e.g. 1 second).
BRANCH=none
BUG=b:63685117
TEST=Flash hammer, timestamps are reported in HID descriptor.
Change-Id: Ie5d56a9df14e464d2cdcd559f550d6e3cc81961f
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/603041
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
fb58920c9e