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 <alan@redhat.com>
Tested-by: Mirko Parthey <mirko.parthey@informatik.tu-chemnitz.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index cf8add9..0da1df9 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -483,6 +483,13 @@
}
spin_unlock_irqrestore(&priv->lock, flags);
+ /* The PL2303 is reported to lose bytes if you change
+ serial settings even to the same values as before. Thus
+ we actually need to filter in this specific case */
+
+ if (!tty_termios_hw_change(port->tty->termios, old_termios))
+ return;
+
cflag = port->tty->termios->c_cflag;
buf = kzalloc(7, GFP_KERNEL);