Re: PROBLEM: Logitech G29 driving wheel input events are garbage if device is opened too soon after plugging in

Re: PROBLEM: Logitech G29 driving wheel input events are garbage if device is opened too soon after plugging in

[Raul Tambre]

Re-sending due to a technical issue resulting in the email being 
rejected by the mailing list.

On 25/05/2020 16:19, Raul Tambre wrote:
>
> When Logitech's "G29 Driving Force Racing Wheel" is plugged in and a 
> program opens it too quickly after that (<120ms), then writing an 
> autocenter effect returns EINVAL and values for input events are garbage.
>
> *Example*
> I've attached a C program that helps reproduce the issue.
> It detects the wheel being plugged in using inotify and applies an 
> autocenter effect. It also prints out input events.
>
> The default device the example opens is /dev/steering_wheel. The 
> device name can be changed in the WHEEL_DEVICE define.
> Add an udev rule to make the steering wheel appear with a fixed name 
> under /dev, e.g.:
> SUBSYSTEM=="input", ATTRS{idVendor}=="046d", ATTRS{idProduct}=="c24f", 
> SYMLINK+="steering_wheel"
>
> Steps:
> 1. Connect the wheel.
> 2. Run the program. An autocenter force should be applied.
> 3. Remove the wheel's USB cable from your computer. You should see 
> "wheel disconnected".
> 4. Plug it back in. The wheel should start its homing sequence.
> 5. The write() in write_autocenter() should fail with EINVAL and the 
> printed input events should be garbage.
>
> *Workaround*
> Sleeping before opening the device after it is reconnected avoids the 
> problem. This can be done through the SLEEP_MS define in the example.
> A value higher than roughly 120ms avoids the issue on my machine.
>
> *Input events*
> With the wheel connected before the program started:
> type=3 code=0 value=32914
> type=0 code=0 value=0
> type=3 code=0 value=32913
> type=0 code=0 value=0
> type=3 code=0 value=32912
> type=0 code=0 value=0
> type=3 code=0 value=32911
>
> When re-connecting the wheel while the program is running:
> type=58304 code=4187 value=243335168
> type=58304 code=4187 value=293666816
> type=58304 code=4187 value=343998464
> type=58304 code=4187 value=394330112
> type=58304 code=4187 value=25329665
> type=58304 code=4187 value=75628544
> type=58304 code=4187 value=75628544
> type=62336 code=4187 value=16941055
> type=62336 code=4187 value=16941055
> type=62336 code=4187 value=16941055
>
> *Kernel version* (/proc/version)
> Linux version 5.7.0-rc5-amd64 (debian-kernel@lists.debian.org) (gcc 
> version 9.3.0 (Debian 9.3.0-12), GNU ld (GNU Binutils for Debian) 
> 2.34) #1 SMP Debian 5.7~rc5-1~exp1 (2020-05-10)
>
> /proc/cpuinfo, /proc/modules, /proc/ioports, /proc/iomem, lspci -vvv 
> and usb-devices outputs are attached.
> The system is an up-to-date Debian Unstable installation.
>