I moved the initialization and clean up code from the init_callback/release callback to the port_init/port_remove callback. This did not help. What prevents the driver from crashing is to initialize the spinlock via spin_lock_init(&priv->lock). Not sure if I originally had forgotten the command, and the driver worked despite an uninitialized spinlock with kernel V3.17, or whether the spin_lock_init procedure was added in kernel version later than 3.17. When issuing a write command to the driver via echo "text" > /dev/ttyUSB0, there is a delay of about 30 Seconds until echo completes (echo is blocking for 30 seconds). This is also observable in the syslog. usbrsa_close is started only around 30 secs after completion of the write function usbrsa_write and the write completion handlers. I would think this might be related to a change in the scheduling mechanism since 3.17. I wonder whether this can be fixed by using usb_serial_port_softint(port) at the right places. It apparently calls the kernel schedulding interface ( usb_serial_port_softint calls schedule_work). I would appreciate a hint on how to prevent the blocking and an explanaion of what usb_serial_port_softint is intented to do. Many thanks Tilman [ 7315.882927] usbrsa ttyUSB0: usbrsa_write_callback - length = 2, data = 0d 0a [ 7315.882932] usbrsa ttyUSB0: usbrsa_write_callback(): Returned URB 1 [ 7315.882938] usbrsa_status_callback: nofTxBytesFree=4074,nofRxBytesReceived=0 [ 7315.883002] usbrsa_status_callback: nofTxBytesFree=4072,nofRxBytesReceived=0 [ 7346.332061] usbrsa_close - start [ 7346.332070] usbrsa ttyUSB0: usbrsa_close - port 0 start [ 7346.332076] usbrsa ttyUSB0: send_baudrate_lcr_register() CFLAG=3261 [ 7346.332080] usbrsa ttyUSB0: send_baudrate_lcr_register() ST16C550.DLL=50;ST16C550.DLM=0;ST16C550.LCR=3 [ 7346.332130] usbrsa ttyUSB0: usbrsa_baudrate_lcr_callback() - port = 0, ep=0xc0028300 [ 7346.332142] usbrsa ttyUSB0: send_baudrate_lcr_register() leaving [ 7346.332146] usbrsa ttyUSB0: usbrsa_close - #retries=3 [ 7346.332148] usbrsa_close - end [ 7346.332151] usbrsa ttyUSB0: usbrsa_close - end [ 7346.332163] usbrsa ttyUSB0: usbrsa_status_callback(): wake_up -- 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
