[PATCH 1/6] USB: serial: cp210x: return early on unchanged termios

Johan Hovold
2020-11-16T16:18:47Z

Return early from set_termios() in case no relevant terminal settings
have changed.

This avoids testing each parameter in turn and specifically allows the
line-control handling to be cleaned up further.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/usb/serial/cp210x.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index d0c05aa8a0d6..f1fd109d97d5 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -1352,6 +1352,15 @@ static void cp210x_disable_event_mode(struct usb_serial_port *port)
port_priv->event_mode = false;
}

+static bool cp210x_termios_change(const struct ktermios *a, const struct ktermios *b)
+{
+ bool iflag_change;
+
+ iflag_change = ((a->c_iflag ^ b->c_iflag) & INPCK);
+
+ return tty_termios_hw_change(a, b) || iflag_change;
+}
+
static void cp210x_set_termios(struct tty_struct *tty,
struct usb_serial_port *port, struct ktermios *old_termios)
{
@@ -1359,6 +1368,9 @@ static void cp210x_set_termios(struct tty_struct *tty,
unsigned int cflag, old_cflag;
u16 bits;

+ if (!cp210x_termios_change(&tty->termios, old_termios))
+ return;
+
cflag = tty->termios.c_cflag;
old_cflag = old_termios->c_cflag;

--
2.26.2