Commit 8cce3bbf authored by Johan Hovold's avatar Johan Hovold
Browse files

USB: serial: cp210x: fix modem-control handling 



The vendor request used to set the flow-control settings also sets the
state of the modem-control lines.

Add state variables to keep track of the modem-control lines to avoid
always asserting the lines whenever the flow-control settings are
updated.

This specifically also avoids asserting DTR/RTS when opening a port with
the line speed set to B0.

Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
parent 5951b850

drivers/usb/serial/cp210x.c

+16 −4
Original line number Diff line number Diff line
@@ -269,6 +269,8 @@ struct cp210x_port_private { 


	struct mutex		mutex;

	bool			crtscts;

	bool			dtr;

	bool			rts;

};



static struct usb_serial_driver cp210x_device = {
@@ -1162,7 +1164,10 @@ static void cp210x_set_flow_control(struct tty_struct *tty, 
	ctl_hs &= ~CP210X_SERIAL_DCD_HANDSHAKE;

	ctl_hs &= ~CP210X_SERIAL_DSR_SENSITIVITY;

	ctl_hs &= ~CP210X_SERIAL_DTR_MASK;

	if (port_priv->dtr)

		ctl_hs |= CP210X_SERIAL_DTR_SHIFT(CP210X_SERIAL_DTR_ACTIVE);

	else

		ctl_hs |= CP210X_SERIAL_DTR_SHIFT(CP210X_SERIAL_DTR_INACTIVE);



	if (C_CRTSCTS(tty)) {

		ctl_hs |= CP210X_SERIAL_CTS_HANDSHAKE;
@@ -1172,7 +1177,10 @@ static void cp210x_set_flow_control(struct tty_struct *tty, 
	} else {

		ctl_hs &= ~CP210X_SERIAL_CTS_HANDSHAKE;

		flow_repl &= ~CP210X_SERIAL_RTS_MASK;

		if (port_priv->rts)

			flow_repl |= CP210X_SERIAL_RTS_SHIFT(CP210X_SERIAL_RTS_ACTIVE);

		else

			flow_repl |= CP210X_SERIAL_RTS_SHIFT(CP210X_SERIAL_RTS_INACTIVE);

		port_priv->crtscts = false;

	}
@@ -1287,25 +1295,29 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port, 
	u16 control = 0;

	int ret;



	mutex_lock(&port_priv->mutex);



	if (set & TIOCM_RTS) {

		port_priv->rts = true;

		control |= CONTROL_RTS;

		control |= CONTROL_WRITE_RTS;

	}

	if (set & TIOCM_DTR) {

		port_priv->dtr = true;

		control |= CONTROL_DTR;

		control |= CONTROL_WRITE_DTR;

	}

	if (clear & TIOCM_RTS) {

		port_priv->rts = false;

		control &= ~CONTROL_RTS;

		control |= CONTROL_WRITE_RTS;

	}

	if (clear & TIOCM_DTR) {

		port_priv->dtr = false;

		control &= ~CONTROL_DTR;

		control |= CONTROL_WRITE_DTR;

	}



	mutex_lock(&port_priv->mutex);



	/*

	 * SET_MHS cannot be used to control RTS when auto-RTS is enabled.

	 * Note that RTS is still deasserted when disabling the UART on close.