On Tue, 2 Apr 2013, Yegor Yefremov wrote: > On Tue, Apr 2, 2013 at 4:14 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > On Tue, 2 Apr 2013, Yegor Yefremov wrote: > > > >> I'm making a burn-in test (see serialtest.py > >> http://pastebin.com/pz47gaar) for our devices, that have built-in FTDI > >> chips. If FT2232C is attached directly to the USB host controller > >> port, the tests run properly. If I connect the chip to a USB-hub some > >> of the tests show timeout errors (read() routine). On the newer host > >> with USB3.0 this issue occurs on all USB ports where I attach FT2232C. > >> I tried kernels 3.2, 3.5 and 3.8. > >> > >> The test procedure opens two ports, exchanges data and closes ports. > >> If I don't open/close ports I don't encounter this issue. > >> > >> The FT4232H has no problems whether I attach it to USB HC or via HUB. > >> Any idea how to workaround the problem? > > > > If you use a different type of hub, does the test work? > > So far I tested with 3 different hub chips SMSC, GL (USB2.0) and one > USB3.0 hub - no difference. In that case, try collecting two usbmon traces showing what happens during the test. In one trace, connect the FT2232C directly to the computer port; in the other, go through the GL hub. See Documentation/usb/usbmon.txt for instructions. By the way, do the errors still occur if you attach the hub to a USB-2 port? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
