USB3.0 bandwidth limitation problem

[rossihwang]

• Hardware

  • host: PC, ubuntu 20.04

  • slave: sg130gs(1280*720, YUYV, 30fps) + fpga(spartan 6) + cyusb3014, isochronous mode

• Problem

  • Can't open the third camera with error(No space left). while currently the bandwidth of one camera is about 8 * 2 * 1024 * (1000000 / 125) / (1024**2) = 125Mbps(bInterval=1, bMaxBurst=7, Mult=1), for two is 250Mbps, much less than 90%(from USB3.0 spec) of the 5000Mbps, why can't it allocate bandwidth for the third camera?

Thanks