linux-imx

HID: input: simplify/fix high-res scroll event handling

Commit 1ff2e1a44e02 ("HID: input: Create a utility class for counting
scroll events") created the helper function

    hid_scroll_counter_handle_scroll()

to handle high-res scroll events and also expose them as regular wheel
events.

But the resulting algorithm was unstable, and causes scrolling to be
very unreliable.  When you hit the half-way mark of the highres
multiplier, small highres movements will incorrectly translate into big
traditional wheel movements, causing odd jitters.

Simplify the code and make the output stable.

NOTE! I'm pretty sure this will need further tweaking.  But this at
least turns a unusable mouse wheel on my Logitech MX Anywhere 2S into
a usable one.

Cc: Jiri Kosina <jikos@kernel.org>
Cc: Harry Cutts <hcutts@chromium.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>