Re: [PATCH v3] HID: logitech-headset: add a battery driver for the PRO X 2

[Jiri Kosina]

On Sun, 11 Oct 2026, Méven Car wrote:

> The PRO X 2 LIGHTSPEED receiver does not speak HID++, so
> hid-logitech-hidpp cannot read its battery. Its report descriptor has a
> consumer collection for the media keys and two vendor collections, and
> no report 0x10 or 0x11.
> 
> The battery answers on usage page 0xffa0. A single 64 byte frame on
> report 0x51 asks for it, with no handshake, and the reply gives the
> level and whether the headset is charging. The driver asks every 120
> seconds. It also reads the power frames that the headset sends on its
> own. A switch-off frame marks the headset absent at once, and a
> switch-on frame moves the next request to one second later, so the level
> appears without waiting for the poll.
> 
> hid-generic sets HID_QUIRK_INPUT_PER_APP, so this receiver had one input
> device per application collection, among them the Consumer Control node
> for the media keys. A driver does not inherit that quirk, so probe sets
> it and the input devices stay as they were.
> 
> The power supply is registered with POWER_SUPPLY_SCOPE_DEVICE. The
> headset is present from a reply until the next switch-off frame, and
> capacity returns -ENODATA while it is absent, so a headset that is off
> when the driver binds reports no level.
> 
> The G522 LIGHTSPEED uses the same vendor protocol with a different frame
> layout. That device is left out until someone can test it.
> 
> Assisted-by: Claude:claude-opus-5
> Signed-off-by: Méven Car <meven@xxxxxxx>
> ---
> Changes in v3:
> - Request the battery level one second after a power-on frame, so the
>   level appears without waiting for the 120 second poll.
> - Report the headset as absent until the first battery reply, and return
>   -ENODATA for capacity while it is absent.
> - Queue the poll on system_dfl_wq instead of the system_wq.
> 
>  drivers/hid/Kconfig                |  11 +
>  drivers/hid/Makefile               |   1 +
>  drivers/hid/hid-ids.h              |   1 +
>  drivers/hid/hid-logitech-headset.c | 319 +++++++++++++++++++++++++++++
>  4 files changed, 332 insertions(+)
>  create mode 100644 drivers/hid/hid-logitech-headset.c
> 
> diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> index 48934c4f3..5c845b1b8 100644
> --- a/drivers/hid/Kconfig
> +++ b/drivers/hid/Kconfig
> @@ -670,6 +670,17 @@ config HID_LOGITECH_DJ
>  	generic USB_HID driver and all incoming events will be multiplexed
>  	into a single mouse and a single keyboard device.
>  
> +config HID_LOGITECH_HEADSET
> +	tristate "Logitech wireless headset battery"
> +	depends on USB_HID
> +	select POWER_SUPPLY
> +	help
> +	Support for the battery of Logitech wireless gaming headsets that
> +	report it over a vendor collection instead of HID++.

Thanks a lot for the patch.

One question though -- is it really practical to have this as a user 
selectable option?
I think it'd make sense to have just selected by HID_LOGITECH_DJ the same 
way as it selects HID_LOGITECH_HIDPP. What do you think?

Thanks,

-- 
Jiri Kosina
SUSE Labs