On Tue, Aug 14, 2018 at 7:33 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 14 Aug 2018, Muni Sekhar wrote: > >> On Mon, Aug 13, 2018 at 7:52 PM, Muni Sekhar <munisekharrms@xxxxxxxxx> wrote: >> > On Mon, Aug 13, 2018 at 6:57 PM, Oliver Neukum <oneukum@xxxxxxxx> wrote: >> >> On Mo, 2018-08-13 at 18:44 +0530, Muni Sekhar wrote: >> >>> [ Please keep me in CC as I'm not subscribed to the list] >> >>> >> >>> Hello All, >> >>> >> >>> I’ve a FTDI serial device and it is not recognized if I connect >> >>> directly to computer. However if I connect via an external USB hub >> >>> it’s fine and I can see the FTDI serial device. What could be the >> >>> issue and how to resolve this? >> If I connect the FTDI device directly to computer I don't see any >> dmesg log, but after enabling the dynamic debugging for usbcore and >> hcd's driver then I see kernel log flooded with the below mentioned >> logs. Is it a bug in the hcd's driver? The same device works fine if I >> connect via an external USB hub. >> >> [14045.942047] hub 2-0:1.0: state 7 ports 6 chg 0000 evt 0004 >> [14045.942156] usb usb2-port2: status 0100, change 0001, 12 Mb/s >> [14046.102357] usb usb2-port2: debounce total 125ms stable 100ms status 0x101 >> [14046.158579] hub 2-0:1.0: state 7 ports 6 chg 0000 evt 0004 >> [14046.158692] usb usb2-port2: status 0100, change 0001, 12 Mb/s >> [14046.318662] usb usb2-port2: debounce total 125ms stable 100ms status 0x101 >> [14046.374689] hub 2-0:1.0: state 7 ports 6 chg 0000 evt 0004 >> [14046.374798] usb usb2-port2: status 0100, change 0001, 12 Mb/s >> [14046.535001] usb usb2-port2: debounce total 125ms stable 100ms status 0x101 >> [14046.591050] hub 2-0:1.0: state 7 ports 6 chg 0000 evt 0004 >> [14046.591161] usb usb2-port2: status 0100, change 0001, 12 Mb/s >> [14046.751382] usb usb2-port2: debounce total 125ms stable 100ms status 0x101 >> [14046.807415] hub 2-0:1.0: state 7 ports 6 chg 0000 evt 0004 >> [14046.807527] usb usb2-port2: status 0100, change 0001, 12 Mb/s >> [14046.967725] usb usb2-port2: debounce total 125ms stable 100ms status 0x101 >> [14047.023761] hub 2-0:1.0: state 7 ports 6 chg 0000 evt 0004 >> [14047.023872] usb usb2-port2: status 0100, change 0001, 12 Mb/s >> [14047.184025] usb usb2-port2: debounce total 125ms stable 100ms status 0x101 >> [14047.240078] hub 2-0:1.0: state 7 ports 6 chg 0000 evt 0004 > > These messages indicate the device is electronically detaching itself > from the bus and then reattaching itself, over and over again, about > four times per second. Thanks for this information. > > Have you tried using this device on another computer? Do you have > another full-speed device you can try plugging into that port? It connects perfectly to my virtual box running Linux. Right now I don't have any other full-speed device to verify this. > > Alan Stern > -- Thanks, Sekhar
