On Mon, 9 May 2011, Alan Cox wrote: > > What has happened is that the API now blocks when a Serial device is not > > indicating it is ready. This included 'open' on a serial device which > > now can block. > > The API has always specified that (its required by POSIX). Some hardware > now gained support for it that was lacking > > > Since lots of RS232 serial devices do not bother with any control > > signals such as DCD (data carrier detect) they never indicate they are > > ready and open blocks. This is the 'HANG' we are seeing. .." > > You can open a port with O_NDELAY, you can also set the port flags to > indicate no flow control via the termios functions. Or before running your program, you can do: stty --file=/dev/usb/tty0 clocal which will tell the kernel to ignore the control signals. I think this will work even if you're unable to modify the program itself (for example, if the source code isn't available). 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
