From bf5e5834bffc62b50cd4a201804506eb11ef1af8 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Tue, 8 Jan 2008 14:55:51 +0000 Subject: pl2303: Fix mode switching regression Cleaning out all the incorrect 'no change made' checks for termios settings showed up a problem with the PL2303. The hardware here seems to lose sync and bits if you tell it to make no changes. This shows up with a real world application. To fix this the driver check for meaningful hardware changes is restored but doing the tests correctly and as a tty layer function so it doesn't get duplicated wrongly everywhere if other drivers turn out to need it. Signed-off-by: Alan Cox Tested-by: Mirko Parthey Signed-off-by: Linus Torvalds --- drivers/char/tty_ioctl.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'drivers/char') diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c index e02d59245a1..d4b6d64e858 100644 --- a/drivers/char/tty_ioctl.c +++ b/drivers/char/tty_ioctl.c @@ -364,6 +364,25 @@ void tty_termios_copy_hw(struct ktermios *new, struct ktermios *old) EXPORT_SYMBOL(tty_termios_copy_hw); +/** + * tty_termios_hw_change - check for setting change + * @a: termios + * @b: termios to compare + * + * Check if any of the bits that affect a dumb device have changed + * between the two termios structures, or a speed change is needed. + */ + +int tty_termios_hw_change(struct ktermios *a, struct ktermios *b) +{ + if (a->c_ispeed != b->c_ispeed || a->c_ospeed != b->c_ospeed) + return 1; + if ((a->c_cflag ^ b->c_cflag) & ~(HUPCL | CREAD | CLOCAL)) + return 1; + return 0; +} +EXPORT_SYMBOL(tty_termios_hw_change); + /** * change_termios - update termios values * @tty: tty to update -- cgit v1.2.3-18-g5258