On Fri, 7 Apr 2006, Paul Fulghum wrote:
> On Thu, 2006-04-06 at 23:48 +0200, Guennadi Liakhovetski wrote:
> > The patch below fixes the Oops, and gets some output with
> > "console=ttyUSB0". But it is not perfect - newlines are not accompanied by
> > carriage returns, and funnily, although in dmesg it says:
> >
> > usb 4-2: FTDI USB Serial Device converter now attached to ttyUSB0
> >
> > after boot running "stty -F /dev/ttyUSB0" produces "no device".
> >
> > So, further fixes would be highly appreciated. Although, I don't know if
> > these problems are specific to ftdi_sio, or to all USB-serial dongles -
> > don't have any other to compare.
>
> Try this patch to fix the ENODEV and CR issues.
Yep, the patch helps against both bugs! Thanks! Are you going to submit it
to the mainline?
> I think usb/drivers/console.c usb_console_setup should be altered
> to provide the dummy tty struct to both the device open and
> device set_termios instead of patching individual drivers
> to check for tty == NULL. The comments seem to indicate that
> was the original intention.
Well, I don't know what's correct, I just saw other drivers doing that.
But, from a quick look, for the first call to ->open() in
usb_console_setup() one would have to setup quite a bit of stuff - a dummy
tty + dummy termios with some meaningful values, for example with ftdi_sio
it would cause ftdi_set_termios() to be called which would do some setup,
which is anyway unneeded, since usb_console_setup() later on anyway calls
->set_termios(). Whereas with my patch you just check for NULL and skip
the redundant (?) call to ftdi_set_termios() altogether. So, this way at
the very least you save a couple of CPU cycles:-)
Oh, btw, Greg, sorry, just realised that I forgot the "Signed-off-by" line
with my patch. Should I resend it?
Thanks
Guennadi
>
> --- linux-2.6.16/drivers/usb/serial/console.c 2006-03-19 23:53:29.000000000
> -0600
> +++ b/drivers/usb/serial/console.c 2006-04-07 13:16:49.000000000 -0500
> @@ -216,11 +216,23 @@ static void usb_console_write(struct con
> goto exit;
> }
>
> - /* pass on to the driver specific version of this function if it is
> available */
> - if (serial->type->write)
> - retval = serial->type->write(port, buf, count);
> - else
> - retval = usb_serial_generic_write(port, buf, count);
> + while (count) {
> + /* pass on to the driver specific version of this function if
> it is available */
> + if (serial->type->write)
> + retval = serial->type->write(port, buf, 1);
> + else
> + retval = usb_serial_generic_write(port, buf, 1);
> + if (*buf == 10) {
> + /* append CR after LF */
> + unsigned char cr = 13;
> + if (serial->type->write)
> + retval = serial->type->write(port, &cr, 1);
> + else
> + retval = usb_serial_generic_write(port, &cr, 1);
> + }
> + buf++;
> + count--;
> + }
>
> exit:
> dbg("%s - return value (if we had one): %d", __FUNCTION__, retval);
> --- linux-2.6.16/drivers/usb/serial/usb-serial.c 2006-03-19
> 23:53:29.000000000 -0600
> +++ b/drivers/usb/serial/usb-serial.c 2006-04-07 13:11:24.000000000 -0500
> @@ -217,6 +217,10 @@ static int serial_open (struct tty_struc
> retval = serial->type->open(port, filp);
> if (retval)
> goto bailout_module_put;
> + } else if (port->tty == NULL) {
> + /* port used as console */
> + tty->driver_data = port;
> + port->tty = tty;
> }
>
> up(&port->sem);
>
>
>
---
Guennadi Liakhovetski
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