Usb webcam on arria 10

I have been trying to use a USB webcam on arria 10 SoC dev-kit, board (using the usual v42l/uvcvideo), but not having much luck.
Issue seems to be driver related with usb interrupt controllers using 30-40% CPU and killing the achievable frame-rate. Specifically;

Have tried multiple(=3) webcams and multiple kernel source versions, but have not found any working combination. In general, problem seems to be less severe on older kernels:

  • 3.10-ltsi* or 4.1.22-ltsi* just about useable with
    640x480@ <20FPS and crazy CPU util
  • 4.11 or 4.10 basically unuseable

Looking at threads from other distro forums, similar issues do sometimes appear, but these are pretty ancient threads and seemingly only ever fixed by kernel update.

Has anybody seen this problem?
or can anyone with a properly working webcam post their .config?

btw. i’d prefer to use >= 4.10, since kmalloc with GFP_DMA seems to fail on kernels before that.