Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=20620d688ac6ff8ea01a873e46febf5a6a7909f1
Commit:     20620d688ac6ff8ea01a873e46febf5a6a7909f1
Parent:     187226f57f1381cfc63216979b4375f30e593795
Author:     David Woodhouse <[EMAIL PROTECTED]>
AuthorDate: Wed Aug 22 14:01:11 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Wed Aug 22 19:52:44 2007 -0700

    serial: don't optimise away baud rate changes when BOTHER is used
    
    The uart_set_termios() function will bail out early without bothering to
    touch the hardware, if it decides that nothing "relevant" has changed.
    Unfortunately, its idea of "relevant" doesn't include c_[io]speed.  So if
    the baud rate bits are BOTHER and you just change the speed, the change
    gets optimised away.
    
    This patch makes it ignore the old Bfoo bits in c_cflag and just check
    whether c_ispeed and c_ospeed have changed.  Those integers are always set
    appropriately for us by set_termios().
    
    Signed-off-by: David Woodhouse <[EMAIL PROTECTED]>
    Acked-by: Alan Cox <[EMAIL PROTECTED]>
    Cc: Russell King <[EMAIL PROTECTED]>
    Cc: Mariusz Kozlowski <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 drivers/serial/serial_core.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 030a606..a055f58 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1146,11 +1146,14 @@ static void uart_set_termios(struct tty_struct *tty, 
struct ktermios *old_termio
 
        /*
         * These are the bits that are used to setup various
-        * flags in the low level driver.
+        * flags in the low level driver. We can ignore the Bfoo
+        * bits in c_cflag; c_[io]speed will always be set
+        * appropriately by set_termios() in tty_ioctl.c
         */
 #define RELEVANT_IFLAG(iflag)  ((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
-
        if ((cflag ^ old_termios->c_cflag) == 0 &&
+           tty->termios->c_ospeed == old_termios->c_ospeed &&
+           tty->termios->c_ispeed == old_termios->c_ispeed &&
            RELEVANT_IFLAG(tty->termios->c_iflag ^ old_termios->c_iflag) == 0)
                return;
 
-
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