diff mbox series

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

Message ID 20210705082015.18286-3-johan@kernel.org (mailing list archive)
State Accepted
Commit ba4bbdabecd11530dca78dbae3ee7e51ffdc0a06
Headers show
Series USB: serial: cp210x: fixes and CP2105/CP2108 fw version | expand

Commit Message

Johan Hovold July 5, 2021, 8:20 a.m. UTC
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 mbox series

Patch

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);
 }