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: Johan Hovold <johan@xxxxxxxxxx>
---
drivers/usb/serial/cp210x.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index 7e4a09b42c99..9378b4bba34b 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -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;
- ctl_hs |= CP210X_SERIAL_DTR_SHIFT(CP210X_SERIAL_DTR_ACTIVE);
+ 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;
- flow_repl |= CP210X_SERIAL_RTS_SHIFT(CP210X_SERIAL_RTS_ACTIVE);
+ 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.
--
2.26.2
