Device gets re-detected but with fewer axes

[code-monet]

I have a wheel that, as far as I can tell, is only misbehaving with Joystick Gremlin. The device starts off being detected as:

[2025-11-02 16:28:15.651] [debug] [info] {91A5C840-6C71-11EF-8002-444553540000}: Processing device: VelocityOne Race
[2025-11-02 16:28:15.658] [debug] [info] Device summary: VelocityOne Race {91A5C840-6C71-11EF-8002-444553540000}
[2025-11-02 16:28:15.658] [debug] [info] Axis=7 Buttons=124 Hats=2
[2025-11-02 16:28:15.658] [debug] [info] Axis map
[2025-11-02 16:28:15.658] [debug] [info]   linear=1 id=1
[2025-11-02 16:28:15.658] [debug] [info]   linear=2 id=2
[2025-11-02 16:28:15.658] [debug] [info]   linear=3 id=3
[2025-11-02 16:28:15.658] [debug] [info]   linear=4 id=4
[2025-11-02 16:28:15.658] [debug] [info]   linear=5 id=5
[2025-11-02 16:28:15.658] [debug] [info]   linear=6 id=6
[2025-11-02 16:28:15.658] [debug] [info]   linear=7 id=7
[2025-11-02 16:28:15.658] [debug] [info]   linear=0 id=0

But at some point this happens:

[2025-11-02 17:00:42.124] [debug] [info] {91A5C840-6C71-11EF-8002-444553540000}: Processing device: VelocityOne Race
[2025-11-02 17:00:42.137] [debug] [warning] VelocityOne Race {91A5C840-6C71-11EF-8002-444553540000}: Overriding reported number of axes,  capabilities=7 enumerated=3
[2025-11-02 17:00:42.137] [debug] [info] Device summary: VelocityOne Race {91A5C840-6C71-11EF-8002-444553540000}
[2025-11-02 17:00:42.137] [debug] [info] Axis=3 Buttons=124 Hats=2
[2025-11-02 17:00:42.137] [debug] [info] Axis map
[2025-11-02 17:00:42.137] [debug] [info]   linear=1 id=1
[2025-11-02 17:00:42.137] [debug] [info]   linear=2 id=2
[2025-11-02 17:00:42.137] [debug] [info]   linear=3 id=6
[2025-11-02 17:00:42.137] [debug] [info]   linear=0 id=0
[2025-11-02 17:00:42.137] [debug] [info]   linear=0 id=0
[2025-11-02 17:00:42.137] [debug] [info]   linear=0 id=0
[2025-11-02 17:00:42.137] [debug] [info]   linear=0 id=0
[2025-11-02 17:00:42.137] [debug] [info]   linear=0 id=0

(there are other lines in between but probably not relevant). At this point, the "USB Game Controllers" control panel app still shows all the axes responding, as does the device manufacturer's own PC app.

Have you seen or heard of something like this before? On my end I'll try adding some debug lines to Dill and see what's going on.

[code-monet]

I have confirmed that this bit of code is causing the problem:

        else
        {
            // Some other invalid axis count information returned, simply trust the
            // axis enumeration
            info.axis_count = axis_indices.size();
            for(size_t i=0; i<axis_indices.size(); ++i)
            {
                info.axis_map[i].linear_index = i+1;
                info.axis_map[i].axis_index = axis_indices[i];
            }
            logger->warn(
                "{} {}: Overriding reported number of axes,  capabilities={} enumerated={}",
                info.name,
                guid_to_string(info.device_guid),
                capabilities.dwAxes,
                axis_indices.size()
            );
        }

The heuristic of checking that the axis has a non-zero value to determine if it's "in use" doesn't seem to be documented anywhere and isn't working for my device. After disabling this else case, I have not had any issues. If you can recall why this was added, I can look into fixing this part of the code. My guess is that you don't want to show axes that don't appear to be in use?