From 4473d054ceb572557954f9536731d39b20937b0c Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Wed, 5 Nov 2014 18:41:59 +0100
Subject: [PATCH] USB: cdc-acm: only raise DTR on transitions from B0
Make sure to only raise DTR on transitions from B0 in set_termios.
Also allow set_termios to be called from open with a termios_old of
NULL. Note that DTR will not be raised prematurely in this case.
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/class/cdc-acm.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 6771f884cb82..9d6495424b06 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -985,11 +985,12 @@ static void acm_tty_set_termios(struct tty_struct *tty,
/* FIXME: Needs to clear unsupported bits in the termios */
acm->clocal = ((termios->c_cflag & CLOCAL) != 0);
- if (!newline.dwDTERate) {
+ if (C_BAUD(tty) == B0) {
newline.dwDTERate = acm->line.dwDTERate;
newctrl &= ~ACM_CTRL_DTR;
- } else
+ } else if (termios_old && (termios_old->c_cflag & CBAUD) == B0) {
newctrl |= ACM_CTRL_DTR;
+ }
if (newctrl != acm->ctrlout)
acm_set_control(acm, acm->ctrlout = newctrl);
--
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