Messages in this thread Patch in this message | | | Date | Mon, 3 Mar 2008 23:13:32 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] uart_get_baud_rate: stop mangling termios |
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On Wed, 20 Feb 2008 20:44:06 +0000 Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> Russell King noticed this one: We have to avoid replacing B0 when we pick > a baud rate for a "hung up" port. Ugly but the proper fix is in the tty > layer and means changing the tty<->serial interfaces so we will defer > that for now. > > Signed-off-by: Alan Cox <alan@redhat.com> > > diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-rc2-mm1/drivers/serial/serial_core.c linux-2.6.25-rc2-mm1/drivers/serial/serial_core.c > --- linux.vanilla-2.6.25-rc2-mm1/drivers/serial/serial_core.c 2008-02-19 11:03:01.000000000 +0000 > +++ linux-2.6.25-rc2-mm1/drivers/serial/serial_core.c 2008-02-20 16:22:49.000000000 +0000 > @@ -329,13 +329,15 @@ > * If it's still invalid, we try 9600 baud. > * > * Update the @termios structure to reflect the baud rate > - * we're actually going to be using. > + * we're actually going to be using. Don't do this for the case > + * where B0 is requested ("hang up"). > */ > unsigned int > uart_get_baud_rate(struct uart_port *port, struct ktermios *termios, > struct ktermios *old, unsigned int min, unsigned int max) > { > unsigned int try, baud, altbaud = 38400; > + int hung_up; > upf_t flags = port->flags & UPF_SPD_MASK; > > if (flags == UPF_SPD_HI) > @@ -360,8 +362,10 @@ > /* > * Special case: B0 rate. > */ > - if (baud == 0) > + if (baud == 0) { > + hung_up = 1; > baud = 9600; > + } > > if (baud >= min && baud <= max) > return baud; > @@ -373,7 +377,9 @@ > termios->c_cflag &= ~CBAUD; > if (old) { > baud = tty_termios_baud_rate(old); > - tty_termios_encode_baud_rate(termios, baud, baud); > + if (!hung_up) > + tty_termios_encode_baud_rate(termios, > + baud, baud); > old = NULL; > continue; > } > @@ -382,7 +388,8 @@ > * As a last resort, if the quotient is zero, > * default to 9600 bps > */ > - tty_termios_encode_baud_rate(termios, 9600, 9600); > + if (!hung_up) > + tty_termios_encode_baud_rate(termios, 9600, 9600); > } > > return 0;
drivers/serial/serial_core.c: In function 'uart_get_baud_rate': drivers/serial/serial_core.c:340: warning: 'hung_up' may be used uninitialized in this function
It isn't completely obvious that this is a falsie.
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