linux-kernel - [PATCH v2 3/3] USB: serial: cp210x: Cleaned up CRTSCTS flag code.

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Date:	Fri, 29 Apr 2016 21:22:35 -0500
From:	Konstantin Shkolnyy <konstantin.shkolnyy@...il.com>
To:	johan@...nel.org
Cc:	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Konstantin Shkolnyy <konstantin.shkolnyy@...il.com>
Subject: [PATCH v2 3/3] USB: serial: cp210x: Cleaned up CRTSCTS flag code.

The CRTSCTS flag code cleared (and inconsistently) bits unrelated to
CRTSCTS functionality. It was also harder than necessary to read.

Signed-off-by: Konstantin Shkolnyy <konstantin.shkolnyy@...il.com>
---
Changes in v2:
Improved CRTSCTS fix based on feedback. Dropped get_termios error handling.

 drivers/usb/serial/cp210x.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index da0567c..d3e1dd2 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -988,24 +988,21 @@ static void cp210x_set_termios(struct tty_struct *tty,
 		dev_dbg(dev, "%s - read ulControlHandshake=%08x ulFlowReplace=%08x\n",
 			__func__, ControlHandshake, FlowReplace);
 
+		ControlHandshake &= ~SERIAL_DSR_HANDSHAKE;
+		ControlHandshake &= ~SERIAL_DCD_HANDSHAKE;
+		ControlHandshake &= ~SERIAL_DSR_SENSITIVITY;
+		ControlHandshake &= ~SERIAL_DTR_MASK;
+		ControlHandshake |= SERIAL_DTR_ACTIVE;
 		if (cflag & CRTSCTS) {
-			ControlHandshake &= ~(SERIAL_DTR_MASK |
-				SERIAL_CTS_HANDSHAKE | SERIAL_DSR_HANDSHAKE |
-				SERIAL_DCD_HANDSHAKE | SERIAL_DSR_SENSITIVITY);
-			ControlHandshake |= SERIAL_DTR_ACTIVE;
 			ControlHandshake |= SERIAL_CTS_HANDSHAKE;
-			/* FIXME why clear bits unrelated to flow control */
-			/* FIXME why clear _XOFF_CONTINUE which is never set */
-			FlowReplace &= ~0xffffffff;
+
+			FlowReplace &= ~SERIAL_RTS_MASK;
 			FlowReplace |= SERIAL_RTS_FLOW_CTL;
 			dev_dbg(dev, "%s - flow control = CRTSCTS\n", __func__);
 		} else {
-			ControlHandshake &= ~(SERIAL_DTR_MASK |
-				SERIAL_CTS_HANDSHAKE | SERIAL_DSR_HANDSHAKE |
-				SERIAL_DCD_HANDSHAKE | SERIAL_DSR_SENSITIVITY);
-			ControlHandshake |= SERIAL_DTR_ACTIVE;
-			/* FIXME - why clear bits unrelated to flow control */
-			FlowReplace &= ~0xff;
+			ControlHandshake &= ~SERIAL_CTS_HANDSHAKE;
+
+			FlowReplace &= ~SERIAL_RTS_MASK;
 			FlowReplace |= SERIAL_RTS_ACTIVE;
 			dev_dbg(dev, "%s - flow control = NONE\n", __func__);
 		}
-- 
1.8.4.5