Messages in this thread | | | Date | Tue, 8 Jun 2004 11:49:51 -0400 (EDT) | From | Byron Stanoszek <> | Subject | Behavior of serial usb driver when unplugged |
| |
Hi all,
I'm currently using Linux (2.6.7-rc3) in an embedded system with a 8-port Sealevel SeaLink 2802 USB device. This is a 8-port RS-232/422 device that allocates /dev/ttyUSB0 through /dev/ttyUSB7 when plugged in.
If I have a process talking to one of the ports, e.g. 'cat < /dev/ttyUSB0', and I unplug the USB hub, all ports except ttyUSB0 unregister properly.
Without killing the 'cat' process, plugging the hub back in will make it allocate /dev/ttyUSB1 through /dev/ttyUSB8, thereby offsetting each USB port# by 1.
When killing the 'cat' process at this point, the kernel reports:
drivers/usb/serial/ftdi_sio.c: error from flowcontrol urb drivers/usb/serial/ftdi_sio.c: Error from DTR LOW urb drivers/usb/serial/ftdi_sio.c: Error from RTS LOW urb
and then unregisters /dev/ttyUSB0.
Is there a way to allow "hotplug" of a USB device to reuse /dev/ttyUSB0 regardless if an application still has that particular tty open?
If not, is there a way I could make the serial subsystem can send an EIO errno or some other notification when the serial device is disconnected?
Thanks for your help, -Byron
-- Byron Stanoszek Ph: (330) 644-3059 Systems Programmer Fax: (330) 644-8110 Commercial Timesharing Inc. Email: byron@comtime.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |