| From 8355118123c7e00056f4062aecc39f0cb6b23f6f Mon Sep 17 00:00:00 2001 |
| From: Johan Hovold <johan@kernel.org> |
| Date: Fri, 6 Jan 2017 19:15:12 +0100 |
| Subject: [PATCH] USB: serial: ch341: fix modem-control and B0 handling |
| |
| 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 <stable@vger.kernel.org> |
| Signed-off-by: Johan Hovold <johan@kernel.org> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c |
| index 764d3fc2b1a6..bf669397a304 100644 |
| --- a/drivers/usb/serial/ch341.c |
| +++ b/drivers/usb/serial/ch341.c |
| @@ -363,21 +363,19 @@ static void ch341_set_termios(struct tty_struct *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); |
| + 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); |
| /* Unimplemented: |
| * (cflag & CSIZE) : data bits [5, 8] |
| * (cflag & PARENB) : parity {NONE, EVEN, ODD} |
| -- |
| 2.10.1 |
| |
