Commit a0467a96 authored by Johan Hovold's avatar Johan Hovold

USB: serial: ch341: fix modem-status handling

The modem-status register was read as part of device configuration at
port_probe and then again at open (and reset-resume). During open (and
reset-resume) the MSR was read before submitting the interrupt URB,
something which could lead to an MSR-change going unnoticed when it
races with open (reset-resume).

Fix this by dropping the redundant reconfiguration of the port at every
open, and only read the MSR after the interrupt URB has been submitted.

Fixes: 664d5df9 ("USB: usb-serial ch341: support for DTR/RTS/CTS")
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
parent 56e6d907
...@@ -248,21 +248,11 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv) ...@@ -248,21 +248,11 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
if (r < 0) if (r < 0)
goto out; goto out;
/* expect 0xff 0xee */
r = ch341_get_status(dev, priv);
if (r < 0)
goto out;
r = ch341_set_baudrate_lcr(dev, priv, priv->lcr); r = ch341_set_baudrate_lcr(dev, priv, priv->lcr);
if (r < 0) if (r < 0)
goto out; goto out;
r = ch341_set_handshake(dev, priv->line_control); r = ch341_set_handshake(dev, priv->line_control);
if (r < 0)
goto out;
/* expect 0x9f 0xee */
r = ch341_get_status(dev, priv);
out: kfree(buffer); out: kfree(buffer);
return r; return r;
...@@ -334,14 +324,9 @@ static void ch341_close(struct usb_serial_port *port) ...@@ -334,14 +324,9 @@ static void ch341_close(struct usb_serial_port *port)
/* open this device, set default parameters */ /* open this device, set default parameters */
static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port) static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
{ {
struct usb_serial *serial = port->serial;
struct ch341_private *priv = usb_get_serial_port_data(port); struct ch341_private *priv = usb_get_serial_port_data(port);
int r; int r;
r = ch341_configure(serial->dev, priv);
if (r)
return r;
if (tty) if (tty)
ch341_set_termios(tty, port, NULL); ch341_set_termios(tty, port, NULL);
...@@ -353,6 +338,12 @@ static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port) ...@@ -353,6 +338,12 @@ static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
return r; return r;
} }
r = ch341_get_status(port->serial->dev, priv);
if (r < 0) {
dev_err(&port->dev, "failed to read modem status: %d\n", r);
goto err_kill_interrupt_urb;
}
r = usb_serial_generic_open(tty, port); r = usb_serial_generic_open(tty, port);
if (r) if (r)
goto err_kill_interrupt_urb; goto err_kill_interrupt_urb;
...@@ -619,6 +610,12 @@ static int ch341_reset_resume(struct usb_serial *serial) ...@@ -619,6 +610,12 @@ static int ch341_reset_resume(struct usb_serial *serial)
ret); ret);
return ret; return ret;
} }
ret = ch341_get_status(port->serial->dev, priv);
if (ret < 0) {
dev_err(&port->dev, "failed to read modem status: %d\n",
ret);
}
} }
return usb_serial_generic_resume(serial); return usb_serial_generic_resume(serial);
......
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