Re: [Ftdi-usb-sio-devel] Multiple serial ports on one adapter

[Toan P. <tph...@gm...>]

>From my study of the ftdi kernel driver recently, the ftdi driver
supports multiple ports.
Here is a confirmation of the ftdi driver cleaning up all the ports
upon disconnection.


static void destroy_serial(struct kref *kref)
{
	struct usb_serial *serial;
	struct usb_serial_port *port;
	int i;

	serial = to_usb_serial(kref);

	dbg("%s - %s", __FUNCTION__, serial->type->description);

	serial->type->shutdown(serial);

	/* return the minor range that this device had */
	return_serial(serial);

	for (i = 0; i < serial->num_ports; ++i)
		serial->port[i]->open_count = 0;

	/* the ports are cleaned up and released in port_release() */
	for (i = 0; i < serial->num_ports; ++i)
		if (serial->port[i]->dev.parent != NULL) {
			device_unregister(&serial->port[i]->dev);
			serial->port[i] = NULL;
		}

	/* If this is a "fake" port, we have to clean it up here, as it will
	 * not get cleaned up in port_release() as it was never registered with
	 * the driver core */
	if (serial->num_ports < serial->num_port_pointers) {
		for (i = serial->num_ports; i < serial->num_port_pointers; ++i) {
			port = serial->port[i];
			if (!port)
				continue;
			port_free(port);
		}
	}

	usb_put_dev(serial->dev);

	/* free up any memory that we allocated */
	kfree (serial);
}


On Wed, Jan 7, 2009 at 9:39 AM, Fred Labrosse <ff...@ab...> wrote:
> All,
>
> I need to have multiple RS422 ports on one computer and was looking at buying
> a USB/serial adapter with multiple (2) serial ports. My application is to
> plug two SICK laser scanners (lms200) into the computer.
>
> I have essentially two questions.
>
> The kernel driver help seems to say that it only supports single port adapters
> and I have seen at least one report on the archive of the mailing list saying
> that the driver didn't work with a multiple port adapter.  Is that indeed the
> case?
>
> Second, is there a specific adapter that I should look at?  The one at
> <http://www.easysync.co.uk/index.html?lang=en-uk&target=d11.html> seems
> interesting.  Anybody has any experience with it?  The vendors explicitly say
> that it works with linux (related to the question above).
>
> TIA,
>
> Fred
>
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