Re: [PATCH 4/8] HID: input: use the Resolution Multiplier for high-resolution scrolling
From: Linus Torvalds
Date: Mon Nov 26 2018 - 21:30:28 EST
On Thu, Nov 22, 2018 at 3:28 PM Peter Hutterer <peter.hutterer@xxxxxxxxx> wrote:
>
> The device sends hi-res values of 4, so it should end up as REL_WHEEL_HI_RES
> 30. We are getting 28 instead which doesn't add up to a nice 120.
I think you're just doing the math in the wrong order.
Why don't you just do
update = val * 120 / multiplier
which gives you the expected "30".
It seems you have done the "120 / multiplier" too early, and you force
that value into "wheel_factor". Don't. Do all the calculations
(including all the accumulated ones) in the original values, and only
do the "multiply by 120 and divide by multiplier" at the very end.
Hmm?
Linus