Re: [PATCH 0/2] HID: logitech-hidpp: fix Bolt hi-res wheel handling

[erikhakan]

Hi!

> On Sep 23 2026, Oleksandr Natalenko wrote:
> > Hello.
> >
> > Not sure if I'm testing this right, but with v7.3-rc4 and these two patches scrolling works OK as long as I keep "Scroll Wheel Resolution" in Solaar off. Unlike with unpatched kernel, scrolling doesn't go crazy if I switch between devices. But if I switch "Scroll Wheel Resolution" on, scrolling jumps crazy again.

Okay, the expectation would be that scrolling would remain working
with "Scroll Wheel Resolution" (==high_resolution) either ON or OFF,
but when it's ON, it would also need "Scroll Wheel Diversion"
(==use_hidpp) to be ON (or ignored, but ignore may retain a previous
user setting, so a reconnect after setting that would be good.).

When you tested, do you remember what the setting for Scroll Wheel 
Diversion was? With it set to off, the scroll events will not go 
through the hid++ driver, so if high resolution is turned on, the 
events will be misinterpreted by the generic HID driver that expects
low resolution events.

> Hopefully we've got all of the involved people here.
>
> Honestly, this whole situation has been running for too long: Bolt can't
> be handled as a DJ receiver, and all the quirks I'm seeing here are
> making things even worse, with the "as long as I keep [some user
> settings] off".
>
> Bolt in kernel was adding in 7.3, so I'm going to revert it now, and
> we'll have to have a fully working plan for an eventual inclusion in a
> future kernel version.
>
> Cheers,
> Benjamin

I totally agree that this is the right call, despite this being my first
kernel patch and I was a bit excited to see it roll out :) But of course
I don't want my first contribution to be problematic, so I agree with
reverting it.
For what it's worth, I checked with my G502 Lightspeed mouse, and it too
has incompatibilities between kernel and userspace, but in a rather
oppsite fashion: When "Scroll Wheel Diversion" (=use_hidpp) is turned
ON for it, scrolling stops working altogether, and looking at the code
I think that might actually be true for any device that supports HID++
function 0x2121, i.e. the more modern high resolution scroll.
So, having an incompatibility between the kernel driver and some Solaar
settings would not be new to the Bolt driver, it would just be a
different incompatibility.

But anyway, let's see if Oleksandr can confirm if the issue remains even
with use_hidpp ON. If not, then I think we're hopefully done with at
least the scroll scaling issue, especially if more people can test as
well. But of course there's still the other issue of not being able to
distinguish between devices.

Cheers!
Erik