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

[Oleksandr Natalenko <oleksandr@natalenko.name>]

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Hello.

On úterý 22. září 2026 19:40:26, středoevropský letní čas Erik Håkansson wrote:
> This series aims to fix high-resolution wheel handling for Logitech devices
> connected through Bolt receivers as well as respect user settings for
> scroll behaviour.
> 
> Patch 1 is Rafael Passos’s original implementation:
> 
> https://lore.kernel.org/linux-input/20260904034843.1340846-1-rafael@rcpassos.me/
> 
> His patch routes Bolt wheel movement through the HID++ child, where the
> device’s HiRes Wheel multiplier can be applied. Patch 2 builds on
> Rafael’s work by 1. supporting both high-resolution and low-resolution
> scroll events, and 2. preserving user-selected high-resolution and
> inversion settings.
> 
> The follow-up patch was developed with reference to the patches and
> reported behavior in Magnetar-OS’s `logitech-bolt-hidpp-dkms` repository:
> 
> https://github.com/Magnetar-OS/logitech-bolt-hidpp-dkms/tree/main/patches
> 
> So my assumption right now is that the reason for the divergent results
> people have had with the two different fix approaches (i.e. either passing
> interface 0 and 1 as DJ interfaces, or Rafael's approach), where it works
> for some, and only sometimes, etc. is that with user settings coming from
> Solaar, we may end up in weird states.
> For example, in the original patch, high-resolution events would go through
> the generic HID which would treat each tick as a full wheel event, thus 
> scaling the scroll way too far. That was solved with Rafael's patch but
> that would instead fail to handle low-resolution events if high resolution
> was turned off in Solaar while use_hidpp remained enabled, so a low-resolution
> delta would be treated as high-resolution, which would result instead in a 
> too slow scroll. Possibly, when Oleksandr switched devices, Solaar reapplied
> some saved user settings, which conflicted with the driver logic.
> 
> With this patch, user settings from Solaar (or elsewhere) for high-resolution
> mode and scroll inversion will be respected, 
> and scrolling should work both in high-resolution and low-resolution mode.
> However, if user-space turns off the use_hidpp setting while high_resolution
> remains on, this will route high-resolution scroll events to generic HID.
> Thus, when high_resolution is on for a Bolt device, the driver will
> force use_hidpp to be on during initialisation or reinitialisation, because
> otherwise the scaling issue will return.
> Solaar may still, after driver initialisation, reapply a saved use_hidpp
> setting of off while high_resolution remains on, or the user may change it
> to off, which will cause the issue even with this patch.
> 
> In theory, it should be possible to look at incoming setWheelMode responses
> or notifications and, just like on initialisation, enforce use_hidpp as long
> as high_resolution is set on a Bolt device. However, I don't know how Solaar
> will behave then. There's a risk it will trigger a back-and-forth if Solaar
> reapplies its saved setting after the kernel corrects it. Also, even if that
> doesn't happen, we should respect user choice even for use_hidpp. Perhaps
> the Solaar team can be informed about the problem so they can add a warning
> text.
> 
> Note that I don't have a Bolt mouse to test this with, and my theory is 
> mostly inferred, so I would appreciate very much if people with various
> Bolt mice could test it out. Also great if you try different settings in 
> Solaar, but note that use_hidpp must be on if high_resolution is on, so 
> either set it to on in Solaar, or to ignore.
> 
> Link: https://lore.kernel.org/linux-input/20260712003051.338194-2-erikhakan@gmail.com/
> Link: https://lore.kernel.org/linux-input/20260901-bolt-scroll-fix-v1-1-58bca7ae487f@protonmail.com/
> Link: https://lore.kernel.org/linux-input/LYMlyJcyQt29e1KlLnEoLw@natalenko.name/
> Link: https://lore.kernel.org/linux-input/20260920094508.39682-1-roman.stingler@gmail.com/
> Signed-off-by: Erik Håkansson <erikhakan@gmail.com>
> ---
> Erik Håkansson (1):
>       HID: logitech-hidpp: fix Bolt wheel mode handling
> 
> Rafael Passos (1):
>       HID: logitech-hidpp: fix hi-res scroll for Bolt-connected MX Master
> 
>  drivers/hid/hid-logitech-hidpp.c | 147 ++++++++++++++++++++++++++++++++-------
>  1 file changed, 123 insertions(+), 24 deletions(-)
> ---
> base-commit: 022eb347ff3a48281e7e69c3addcb11bf24afa53
> change-id: 20260921-feature-bolt-fix-5f1f642496df
> 
> Best regards,

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.

-- 
Oleksandr Natalenko, MSE

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