How do I use external web camera though USB OTG on Huawei Honor 6?

Built-in kernel does not come with USB Video support and when using sideloaded uvcvideo.ko the camera works very bad (image is distorted, the device often crash). I can barely get even single 160x120 frames. FFmpeg says [video4linux2,v4l2 @ 0xa57320] The v4l2 frame is 32712 bytes, but 38400 bytes are expected (the bigger frame size, the sooner). dmesg says something like [ 1610.497185] [7168.0, ffmpeg] cma: dma_alloc_from_contiguous(cma e44c14c0, count 10, align 4). I tried various quirks parameters for the uvcvideo.ko module, but nothing helps. How do I make use of external USB camera on my device? Are there any patches/hackes available?