[libusb] usb relay board does not work with linux kernel newer than 5.3.18

[Hans J. M. <ma...@hj...>]

Hi,

maybe this is not the correct forum to place the question because my 
problem seems to
be a kernel problem. I'm operating a usb-relay board based on chip 
ch341a on suse linux
leap 15.2. As a driver program I use a small pure c-program written by 
Edwin van de Oetelaar.
The program worked fine until I upgraded the kernel from 5.3.18-lp152.57 
to 5.3.18-lp152.75.
This happened on several PC's, and also a newer kernel 5.10.4 showed the 
same behavior.
All return codes from routine like

libusb_get_device_list
libusb_open_device_with_vid_pid
libusb_kernel_driver_active
libusb_detach_kernel_driver
libusb_claim_interface
libusb_bulk_transfer

are identical and behave well when calling the program under either 
kernel, however the relays
simply don't work under the newer kernels.

Any idea, what could be the problem. Thanks a lot for looking at my 
question.

hajo