From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f68.google.com ([209.85.215.68]:35240 "EHLO mail-lf0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750982AbdAQPVB (ORCPT ); Tue, 17 Jan 2017 10:21:01 -0500 Received: by mail-lf0-f68.google.com with SMTP id v186so16722893lfa.2 for ; Tue, 17 Jan 2017 07:20:08 -0800 (PST) From: Johan Hovold To: Greg Kroah-Hartman Cc: Johan Hovold , stable Subject: [PATCH stable-4.9] USB: serial: ch341: fix modem-control and B0 handling Date: Tue, 17 Jan 2017 16:19:57 +0100 Message-Id: <20170117151957.18526-1-johan@kernel.org> Sender: stable-owner@vger.kernel.org List-ID: commit 030ee7ae52a46a2be52ccc8242c4a330aba8d38e upstream. The modem-control signals are managed by the tty-layer during open and should not be asserted prematurely when set_termios is called from driver open. Also make sure that the signals are asserted only when changing speed from B0. Fixes: 664d5df92e88 ("USB: usb-serial ch341: support for DTR/RTS/CTS") Cc: stable Signed-off-by: Johan Hovold --- This is a backport of 030ee7ae52a4 ("USB: serial: ch341: fix modem-control and B0 handling") to 4.9 that should apply also to 4.4. Johan drivers/usb/serial/ch341.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c index 3a48302c1cd5..d23dfdd0247d 100644 --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -345,24 +345,24 @@ static void ch341_set_termios(struct tty_struct *tty, baud_rate = tty_get_baud_rate(tty); if (baud_rate) { - spin_lock_irqsave(&priv->lock, flags); - priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS); - spin_unlock_irqrestore(&priv->lock, flags); priv->baud_rate = baud_rate; ch341_set_baudrate(port->serial->dev, priv); - } else { - spin_lock_irqsave(&priv->lock, flags); - priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS); - spin_unlock_irqrestore(&priv->lock, flags); } - ch341_set_handshake(port->serial->dev, priv->line_control); - /* Unimplemented: * (cflag & CSIZE) : data bits [5, 8] * (cflag & PARENB) : parity {NONE, EVEN, ODD} * (cflag & CSTOPB) : stop bits [1, 2] */ + + spin_lock_irqsave(&priv->lock, flags); + if (C_BAUD(tty) == B0) + priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS); + else if (old_termios && (old_termios->c_cflag & CBAUD) == B0) + priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS); + spin_unlock_irqrestore(&priv->lock, flags); + + ch341_set_handshake(port->serial->dev, priv->line_control); } static void ch341_break_ctl(struct tty_struct *tty, int break_state) -- 2.10.2