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pl2303: Fix mode switching regression

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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>
This commit is contained in:
Alan Cox
2008-01-08 14:55:51 +00:00
committed by Linus Torvalds
parent cf05946250
commit bf5e5834bf
3 changed files with 27 additions and 0 deletions
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7
drivers/usb/serial/pl2303.c
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@@ -483,6 +483,13 @@ static void pl2303_set_termios(struct usb_serial_port *port,
}
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);