Re: [PATCH] HID: hid-input: Extend Elan ignore battery quirk to USB

[Dmitry Torokhov <dtor@google.com>]

On Fri, Oct 31, 2025 at 7:47 AM Dmitry Torokhov <dtor@google.com> wrote:
>
> Hi Hans,
>
> On Fri, Oct 31, 2025 at 2:13 AM Hans de Goede <hansg@kernel.org> wrote:
> >
> > Hi Jiri,
> >
> > On 31-Oct-25 10:07 AM, Jiri Kosina wrote:
> > > On Thu, 30 Oct 2025, Mario Limonciello (AMD) wrote:
> > >
> > >> USB Elan devices have the same problem as the I2C ones with a fake
> > >> battery device showing up.
> > >>
> > >> Reviewed-by: Hans de Goede <hansg@kernel.org>
> > >> Reported-by: André Barata <andretiagob@protonmail.com>
> > >> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220722
> > >> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
> > >
> > > Now applied.
> > >
> > > We'll have to come up with something more sophisticated once/if Elan ever
> > > starts producing devices with real battery ...
> >
> > Actually the provided HID battery is intended to be for
> > when a stylus is used and to report the stylus battery
> > values then.
> >
> > There is an email thread somewhere with some of the ChromeOS folks
> > talking about dropping the ELAN quirk for I2C touchscreens and
> > indeed replacing it with something more sophisticated. IIRC
> > the ChromeOS folks mentioned they would work on / provide patches.
> >
> > +To: Dmitry, Dmitry do you have any input on the ChromeOs issue ?
>
> +Kenneth Albanowski has been wrangling with support of Elan and other
> vendor styli, I'll let him comment.

Kenneth is currently busy with some internal projects and asked me to
pass the following:

We recommend that userspace components do not generate alerts for
power supplies that report "status" as "unknown". For a lot of styli
we start with "unknown" and 0 level until after we get a first real
report and update the state to "discharging" or "full" and only hen we
may start showing the indicator.

On ChromeOS we also have tech for clarifying "1%" and other bad
reports, currently specific to USI styluses using a S/N filter.

Kenneth will try to share more details next week hopefully.

Thanks,
Dmitry