Re: HID: logitech-hidpp: G920 FF init fails with -110 since "move FF initialization to .input_configured()"

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Gideon,

On Wed, Nov 04, 2026 at 09:32:04PM +0100, Gideon Heinz wrote:
> The init failure is fixed:
>
>   logitech-hidpp-device 0003:046D:C262.000B: Force feedback support
>   loaded (firmware release 4).
>   logitech-hidpp-device 0003:046D:C262.000B: HID++ 4.2 device connected.
>
> No -110 anymore, and fftest lists all effect types with uploads OK.
>
> One separate observation: when I play the constant effect in fftest,
> dmesg shows "Force feedback command queue contains 20 commands, causing
> substantial delays!" followed by "Failed to send command to device!".
> This doesn't happen on stock Arch 7.2.11 (no patch, old init order).
> I haven't determined whether it's related to the patch, to other 7.3
> changes, or specific to the CachyOS kernel build. I can capture usbmon
> of it if that helps.

Thank you for testing!

Yes, a usbmon capture along with matching dmesg output would be very
helpful. Also, when you played the constant effect, did the wheel
actually produce any force (perhaps after a delay), or was force feedback
completely unresponsive?

Note that hid-logitech-hidpp queues all FF commands (gain, effect
uploads, playback, erase-on-close, and sysfs "range" writes) onto an
asynchronous workqueue, so fftest prints "OK" on upload even if the
worker thread is stalled. If anything queues a command while the input
device is closed and the interrupt IN URB is not running (for instance
cleanup commands from closing an earlier fftest run within ~15 seconds,
or a udev rule writing to the "range" sysfs attribute after probe), the
worker gets stuck waiting 3 x 5s for a reply and later commands pile up
behind it. On the other hand, if commands are timing out while fftest is
the first user and keeping the device open, the inverted init order
(hidpp_connect_event() now running after g920_get_config()) or another
7.3 change may be upsetting the device or endpoint.

If you can start usbmon before loading the patched module (or plugging
the wheel in), wait ~20 seconds after probe settles, and then run fftest
once to trigger the constant effect before exiting, that should tell us
immediately which case it is.

Thanks.

-- 
Dmitry