[PATCH v2 1/6] USB: serial: cp210x: fix control-characters error handling

[PATCH v2 1/6] USB: serial: cp210x: fix control-characters error handling

[Johan Hovold]

In the unlikely event that setting the software flow-control characters
fails the other flow-control settings should still be updated (just like
all other terminal settings).

Move out the error message printed by the set_chars() helper to make it
more obvious that this is intentional.

Fixes: 7748feffcd80 ("USB: serial: cp210x: add support for software flow control")
Cc: stable@vger.kernel.org	# 5.11
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/cp210x.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index 09b845d0da41..fd198031de71 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -1163,10 +1163,8 @@ static int cp210x_set_chars(struct usb_serial_port *port,
 
 	kfree(dmabuf);
 
-	if (result < 0) {
-		dev_err(&port->dev, "failed to set special chars: %d\n", result);
+	if (result < 0)
 		return result;
-	}
 
 	return 0;
 }
@@ -1218,8 +1216,10 @@ static void cp210x_set_flow_control(struct tty_struct *tty,
 		chars.bXoffChar = STOP_CHAR(tty);
 
 		ret = cp210x_set_chars(port, &chars);
-		if (ret)
-			return;
+		if (ret) {
+			dev_err(&port->dev, "failed to set special chars: %d\n",
+					ret);
+		}
 	}
 
 	mutex_lock(&port_priv->mutex);
-- 
2.31.1

[PATCH v2 2/6] USB: serial: cp210x: fix flow-control error handling

[Johan Hovold]

Make sure that the driver crtscts state is not updated in the unlikely
event that the flow-control request fails. Not doing so could break RTS
control.

Fixes: 5951b8508855 ("USB: serial: cp210x: suppress modem-control errors")
Cc: stable@vger.kernel.org	# 5.11
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/cp210x.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index fd198031de71..fd6bd574e2a5 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -1189,6 +1189,7 @@ static void cp210x_set_flow_control(struct tty_struct *tty,
 	struct cp210x_flow_ctl flow_ctl;
 	u32 flow_repl;
 	u32 ctl_hs;
+	bool crtscts;
 	int ret;
 
 	/*
@@ -1248,14 +1249,14 @@ static void cp210x_set_flow_control(struct tty_struct *tty,
 			flow_repl |= CP210X_SERIAL_RTS_FLOW_CTL;
 		else
 			flow_repl |= CP210X_SERIAL_RTS_INACTIVE;
-		port_priv->crtscts = true;
+		crtscts = true;
 	} else {
 		ctl_hs &= ~CP210X_SERIAL_CTS_HANDSHAKE;
 		if (port_priv->rts)
 			flow_repl |= CP210X_SERIAL_RTS_ACTIVE;
 		else
 			flow_repl |= CP210X_SERIAL_RTS_INACTIVE;
-		port_priv->crtscts = false;
+		crtscts = false;
 	}
 
 	if (I_IXOFF(tty)) {
@@ -1278,8 +1279,12 @@ static void cp210x_set_flow_control(struct tty_struct *tty,
 	flow_ctl.ulControlHandshake = cpu_to_le32(ctl_hs);
 	flow_ctl.ulFlowReplace = cpu_to_le32(flow_repl);
 
-	cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl,
+	ret = cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl,
 			sizeof(flow_ctl));
+	if (ret)
+		goto out_unlock;
+
+	port_priv->crtscts = crtscts;
 out_unlock:
 	mutex_unlock(&port_priv->mutex);
 }
-- 
2.31.1