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From: Harry Cutts <>
	Peter Hutterer <>
Subject: Re: Logitech high-resolution scrolling..
Date: Mon, 29 Oct 2018 12:17:12 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

As I explained in the comments, the reason for triggering at the half
multiplier point and then setting a negative remainder is to cater for
wheels that sometimes rest just before they complete a whole "notch"
in clicky mode. On those mice, setting the threshold at a full notch
means that you frequently have to move the wheel a little past its
resting point to trigger the low-res scroll event.

I don't really understand why the half-multiplier thing would cause
the instability; there's still a low-res threshold every 8 high-res
units whichever way you do it, it's just that with the half-multiplier
method it's 4 closer to the point where the wheel was when the device
was connected. Once you've scrolled around a bit in smooth mode that
should be irrelevant, unless you're somehow managing to move the wheel
in whole-notch increments without the help of the ratchet.

Maybe the long-term solution is to use more than just the value of the
current scroll event when deciding whether to send a low-res event. In
the meantime, I'll write a patch putting the threshold at 7/8ths of a
notch, to see if that can solve both issues.


Harry Cutts
Chrome OS Touch/Input team
Harry Cutts
Chrome OS Touch/Input team

On Mon, 29 Oct 2018 at 11:33, Linus Torvalds
<> wrote:
> On Mon, Oct 29, 2018 at 8:16 AM Linus Torvalds
> <> wrote:
> >
> > Patch I'm using attached. I'm inclined to just commit it, but if
> > somebody has a better idea, I can test alternatives too.
> I committed my patch, as it at least makes the scroll wheel usable.
> I'm more than open to further improvements, but I wasn't willing to
> live with the status quo, and carrying this around in my tree as a
> patch kept confusing me while doing merges whenever a conflict
> happened (because the "git diff" that I use to see the conflicts
> obviously also showed my own local modifications).
>                  Linus

  reply	other threads:[~2018-10-29 19:17 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-28 19:13 Linus Torvalds
2018-10-28 21:08 ` Linus Torvalds
2018-10-30 15:53   ` Mauro Carvalho Chehab
2018-10-29 13:18 ` Jiri Kosina
2018-10-29 15:16   ` Linus Torvalds
2018-10-29 18:32     ` Linus Torvalds
2018-10-29 19:17       ` Harry Cutts [this message]
2018-10-29 21:11         ` Linus Torvalds
2018-10-29 21:42           ` Harry Cutts
2018-10-29 22:00             ` Linus Torvalds
2018-10-29 23:03               ` Harry Cutts
2018-10-30  6:26                 ` Peter Hutterer
2018-10-30 16:29                   ` Linus Torvalds
2018-10-30 17:48                     ` Harry Cutts
2018-10-31 13:47                       ` Nestor Lopez Casado

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