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

[Hans de Goede <hansg@kernel.org>]

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 ?

In the mean time I do believe these quirks are the lesser of
2 evils. Most people don't have a stylus (which is typically not
bundled with these devices) and even if people have a stylus
not having battery reporting for that is less of a problem then
the false positive low-battery *notifications* which e.g. GNOME
shows due to the battery reporting 0% (rather then not present)
when there is no stylus.

Regards,

Hans