linux-kernel - Re: usb serial: pl2303 driver TxD "break" stays after close() bug

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Message-ID: <20150220032533.GM12405@localhost>
Date:	Fri, 20 Feb 2015 10:25:33 +0700
From:	Johan Hovold <johan@...nel.org>
To:	Jari Ruusu <jariruusu@...rs.sourceforge.net>
Cc:	Johan Hovold <johan@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: usb serial: pl2303 driver TxD "break" stays after close() bug

On Thu, Feb 19, 2015 at 03:38:39PM +0200, Jari Ruusu wrote:
> On 2/19/15, Johan Hovold <johan@...nel.org> wrote:
> > What happens when you reopen the port? Is the break state cleared then?
> 
> Stuck "break" signal is not cleared on re-open.
> 
> To clear it, you need to poke it with ioctl(fd, TIOCCBRK, 0)
> or disconnect the device.

That's definitely a bug.

Care to test the patch below?

Thanks,
Johan


>From ee3f2d35adc59822d72f3908078da7f361c26577 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@...nel.org>
Date: Fri, 20 Feb 2015 10:05:51 +0700
Subject: [PATCH] USB: pl2303: disable break on shutdown

Currently an enabled break state is not disabled on final close nor on
re-open and has to be disabled manually.

Fix this by disabling break on port shutdown.

Reported-by: Jari Ruusu <jariruusu@...rs.sourceforge.net>
Signed-off-by: Johan Hovold <johan@...nel.org>
---
 drivers/usb/serial/pl2303.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 0f872e6b2c87..f6fe4737185d 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -132,6 +132,7 @@ MODULE_DEVICE_TABLE(usb, id_table);
 #define UART_OVERRUN_ERROR		0x40
 #define UART_CTS			0x80
 
+static void pl2303_set_break(struct usb_serial_port *port, bool enable);
 
 enum pl2303_type {
 	TYPE_01,	/* Type 0 and 1 (difference unknown) */
@@ -613,6 +614,7 @@ static void pl2303_dtr_rts(struct usb_serial_port *port, int on)
 
 static void pl2303_close(struct usb_serial_port *port)
 {
+	pl2303_set_break(port, false);
 	usb_serial_generic_close(port);
 	usb_kill_urb(port->interrupt_in_urb);
 }
@@ -741,17 +743,16 @@ static int pl2303_ioctl(struct tty_struct *tty,
 	return -ENOIOCTLCMD;
 }
 
-static void pl2303_break_ctl(struct tty_struct *tty, int break_state)
+static void pl2303_set_break(struct usb_serial_port *port, bool enable)
 {
-	struct usb_serial_port *port = tty->driver_data;
 	struct usb_serial *serial = port->serial;
 	u16 state;
 	int result;
 
-	if (break_state == 0)
-		state = BREAK_OFF;
-	else
+	if (enable)
 		state = BREAK_ON;
+	else
+		state = BREAK_OFF;
 
 	dev_dbg(&port->dev, "%s - turning break %s\n", __func__,
 			state == BREAK_OFF ? "off" : "on");
@@ -763,6 +764,13 @@ static void pl2303_break_ctl(struct tty_struct *tty, int break_state)
 		dev_err(&port->dev, "error sending break = %d\n", result);
 }
 
+static void pl2303_break_ctl(struct tty_struct *tty, int state)
+{
+	struct usb_serial_port *port = tty->driver_data;
+
+	pl2303_set_break(port, state);
+}
+
 static void pl2303_update_line_status(struct usb_serial_port *port,
 				      unsigned char *data,
 				      unsigned int actual_length)
-- 
2.0.5

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