Where to find the information how to write a state of the art USB driver?

[Philipp Hortmann]

On 1/12/22 10:54 AM, Greg KH wrote:
> That driver tried to be an example for an unknown device, doing multiple
> different things that no single driver/device would probably ever need.
> Also it can almost always just be replaced with a simple userspace
> program using libusb, as I bet your driver could be replaced with as
> well, right?
Yes it can be replaced by a userspace program but even this is not 
required. For the USB LCD a userspace program is available from vendor. 
For the USB to serial Adapter the driver exists in the kernel ch341.c. 
It appears as a ttyUSB0 device.

I think what happens to very custom drivers that could be userspace 
programs can be seen in the file /drivers/usb/misc/usblcd.c
- It is written in 2005 and is only supporting one device from one vendor.
- I cannot find/buy a suitable device.
- I have tried two times to contact the author of the driver but:
The response from the remote server was:
550 5.1.1 <g.toth at e-biz.lu>: Recipient address rejected: User unknown
- The idVendor = 0x10D2 does also not help because RayComposer - R. 
Adams does not response and does not seam to offer such products.

To me it is unused code but how to verify? When it is unused what does 
the kernel do with it? Putting it to the staging area?

Thanks for your time.

Bye Philipp