I'd been telling people to use firejail as a temporary workaround to prevent
steam from seeing the hidraw device. Note that hid-nintendo sets the most
significant bit of the evdev's version number to allow userspace applications
to discern it from the default hid device. There's no current mechanism in
the driver to yield to userspace using hidraw, but I can look at what
hid-steam is currently doing to accomplish that.

I guess the downside to that method is that any other process listening to
the controller's evdev events would cease to receive them (maybe a voice
chat program using one of the buttons as a push-to-talk hotkey or something
similar).

Does steam use hidraw for the sony dualshock controllers as well? If so, is
hid-sony doing anything special for that usecase?

In hid-sony we are not doing anything like hid-steam is doing (no virtual extra hidraw device).

I just don't know how I feel about mixing of evdev and hidraw. It just means userspace drivers are doing things behind the back of the real driver (unless you add a virtual hidraw driver like hid-steam). For Sony devices I'm not a big fan as our devices are very complex. Our devices tend to use a single output report (same report id) for rumble, audio and other types of data. When we will expose audio properly, a user space application doing hidraw will mess up audio streams and other behavior (e.g. power settings are also in the same hid report).

I don't know a good way yet. Has the usage of EVIOCGRAB been explored? If I recall it was intended to claim exclusive access to a device at least for input. It is a way of avoiding of some of the issues for simpler devices.

Virtual devices could work too, but I really dislike the extra complexity to hid drivers. Just in Sony case our driver for future devices will already be quite complex. If we really want virtual device support, I don't think it would scale to add it to every driver. Maybe there would be a generic way in the HID driver in which drivers can blacklist certain reports or hook into just certain requests or so.

Thanks,
Roderick