From: David Woodhouse <[email protected]>
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]>
---
drivers/serial/serial_core.c | 7 +++++--
1 files changed, 5 insertions(+), 2 deletions(-)
diff -puN drivers/serial/serial_core.c~dont-optimise-away-baud-rate-changes-when-bother-is-used drivers/serial/serial_core.c
--- a/drivers/serial/serial_core.c~dont-optimise-away-baud-rate-changes-when-bother-is-used
+++ a/drivers/serial/serial_core.c
@@ -1146,11 +1146,14 @@ static void uart_set_termios(struct tty_
/*
* 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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