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authorDavid Woodhouse <dwmw2@infradead.org>2007-08-23 01:01:11 +0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-08-23 06:52:44 +0400
commit20620d688ac6ff8ea01a873e46febf5a6a7909f1 (patch)
treed96669333a906efd030016267aae93986434487a /drivers/serial/serial_core.c
parent187226f57f1381cfc63216979b4375f30e593795 (diff)
downloadlinux-20620d688ac6ff8ea01a873e46febf5a6a7909f1.tar.xz
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 <dwmw2@infradead.org> Acked-by: Alan Cox <alan@redhat.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Mariusz Kozlowski <m.kozlowski@tuxland.pl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/serial/serial_core.c')
-rw-r--r--drivers/serial/serial_core.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 030a6063541d..a055f58f342f 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;