[PATCH 3.16 196/370] USB: ch341: set tty baud speed according to tty struct

Ben Hutchings
2017-03-10T12:37:07Z

From: Nicolas PLANEL <nicolas.planel@enovance.com>

commit aa91def41a7bb1fd65492934ce6bea19202b6080 upstream.

The ch341_set_baudrate() function initialize the device baud speed
according to the value on priv->baud_rate. By default the ch341_open() set
it to a hardcoded value (DEFAULT_BAUD_RATE 9600). Unfortunately, the
tty_struct is not initialized with the same default value. (usually 56700)

This means that the tty_struct and the device baud rate generator are not
synchronized after opening the port.

Fixup is done by calling ch341_set_termios() if tty exist.
Remove unnecessary variable priv->baud_rate setup as it's already done by
ch341_port_probe().
Remove unnecessary call to ch341_set_{handshake,baudrate}() in
ch341_open() as there already called in ch341_configure() and
ch341_set_termios()

Signed-off-by: Nicolas PLANEL <nicolas.planel@enovance.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/usb/serial/ch341.c | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 2d72aa3564a3..ede4f5fcfadd 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -84,6 +84,10 @@ struct ch341_private {
u8 line_status; /* active status of modem control inputs */
};

+static void ch341_set_termios(struct tty_struct *tty,
+ struct usb_serial_port *port,
+ struct ktermios *old_termios);
+
static int ch341_control_out(struct usb_device *dev, u8 request,
u16 value, u16 index)
{
@@ -309,19 +313,12 @@ static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
struct ch341_private *priv = usb_get_serial_port_data(port);
int r;

- priv->baud_rate = DEFAULT_BAUD_RATE;
-
r = ch341_configure(serial->dev, priv);
if (r)
goto out;

- r = ch341_set_handshake(serial->dev, priv->line_control);
- if (r)
- goto out;
-
- r = ch341_set_baudrate(serial->dev, priv);
- if (r)
- goto out;
+ if (tty)
+ ch341_set_termios(tty, port, NULL);

dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);