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]>
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index e8be3b5..a81fc08 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1146,13 +1146,23 @@ 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
*/
+#ifdef CIBAUD
+#define RELEVANT_CFLAG(cflag) ((cflag) & ~(CIBAUD|CBAUD)
+#else
+#define RELEVANT_CFLAG(cflag) ((cflag) & ~(CBAUD)
+#endif
#define RELEVANT_IFLAG(iflag) ((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
-
if ((cflag ^ old_termios->c_cflag) == 0 &&
- RELEVANT_IFLAG(tty->termios->c_iflag ^ old_termios->c_iflag) == 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) {
+ printk("No relevant change\n");
return;
+ }
uart_change_speed(state, old_termios);
--
dwmw2
-
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