On Sat, Sep 08, 2012 at 04:26:37PM -0500, Caylan Larson wrote: > Hi, > > I have three, 4-port USB-to-Serial adapters connected to a Linux > system running kernel 3.3.7-1. These three adapters are connected to > the system via a USB hub. The application is a DOS app (point of sale > system), running in DOSEMU (DOS emulator), that connects directly to > these serial devices. This logs below coincide with a lock-up of the > production application. We are using software flow control at 38400 > baud, we are not using hardware flow control. Any reason you can't use hardware flow control? > Sep 8 13:44:54 prod05 kernel: [25716.429799] ftdi_sio ttyUSB11: urb failed to clear flow control > Sep 8 13:46:15 prod05 kernel: [25797.281701] ftdi_sio ttyUSB11: ftdi_set_termios FAILED to set databits/stopbits/parity > Sep 8 13:46:16 prod05 kernel: [25798.279805] ftdi_sio ttyUSB11: ftdi_set_termios urb failed to set baudrate > Sep 8 13:46:21 prod05 kernel: [25803.270534] ftdi_sio ttyUSB11: urb failed to clear flow control Something bad happened with the device, and a control message sent to it failed. > More of these messages are repeated for all the serial ports connected to the 3rd adapter (see below). > > Here is the exact model I'm using. And again, 3 of these connected to a USB hub. > > http://www.amazon.com/dp/B004EKI4DC/ref=pe_175190_21431760_M2T1_SC_3p_dp_1 > > This PRO Grade Adapter is build around FT4232H from FTDI > > Semiconductors which is the best and most reliable Quad Serial to > > USB processors on the market it also uses ZT232E RS232 transciever > > from ZyWyn USA. USB cable is 6ft Total Lenght with Port > > Identificaiton marks on each of the DB9 Male ends. > > > It's worth noting that this setup is not a one-off. I have two > production installations of the same size (12 serial ports) and this > is the first I've seen of the issue. The two installations may have > different model hubs. Lastly, the installation (prod05) that > succumbed to this error was running perfectly for 3 days under load - > but this Saturday afternoon was the peak of their business and it > failed. Bummer. > > Does anyone know how to prevent this from happening? As this is a rare occurance, possibly an electrical glitch happened to disrupt the connection to the devices, or the hub caused the problem? I really don't know what happened here, sorry. greg k-h -- 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
