On Wed, Mar 27, 2024 at 12:33:51PM +0100, Martijn Braam wrote: > I hope this is an acceptable place to ask this question. I've spend a bit of > time reverse-engineering the USB protocol for a subset of Blackmagic Design > video mixers and I have made a userspace implementation to make these > devices usable in Linux with libusb. This is working great but the roadblock > I have that I can't find a reasonable solution for is that these devices > also expose an UVC webcam. > > While my control software is active it's not possible to use the UVC webcam > functionality of the device because with libusb I have to detach the kernel > from the interfaces to make my userspace access work. As far as I can find > documented online there's no way to have half a composite device handled by > kernel drivers and half with userspace drivers in Linux. It seems to me the > only solution is to make a kernel driver to bind to the control interface > and have that kernel driver pass-through to userspace somehow with a custom > protocol? If that is the case would such a driver even be supported in > Linux? Why not just make a kernel driver for the interfaces that are not uvc? We would accept that given that you can not control a device from usbfs and a driver at the same time as you have pointed out. thanks, greg k-h
