linux-kernel - [PATCH 1/5] USB: serial: cp210x: Fixed RTS mode setting by the CRTSCTS flag.

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Message-Id: <1458603436-26847-1-git-send-email-konstantin.shkolnyy@gmail.com>
Date:	Mon, 21 Mar 2016 18:37:16 -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 1/5] USB: serial: cp210x: Fixed RTS mode setting by the CRTSCTS flag.

A bug in the CRTSCT handling caused RTS to alternate between
CRTSCTS=0 => "RTS transmits active signal" and
CRTSCTS=1 => "RTS receives flow control"
instead of
CRTSCTS=0 => "RTS is statically active" and
CRTSCTS=1 => "RTS receives flow control"

Signed-off-by: Konstantin Shkolnyy <konstantin.shkolnyy@...il.com>
---
 drivers/usb/serial/cp210x.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index c740592..de1606f 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -955,16 +955,12 @@ static void cp210x_set_termios(struct tty_struct *tty,
 			modem_ctl[0] &= ~0x7B;
 			modem_ctl[0] |= 0x09;
 			modem_ctl[4] = 0x80;
-			/* FIXME - why clear reserved bits just read? */
-			modem_ctl[5] = 0;
-			modem_ctl[6] = 0;
 			modem_ctl[7] = 0;
 			dev_dbg(dev, "%s - flow control = CRTSCTS\n", __func__);
 		} else {
 			modem_ctl[0] &= ~0x7B;
 			modem_ctl[0] |= 0x01;
-			/* FIXME - OR here instead of assignment looks wrong */
-			modem_ctl[4] |= 0x40;
+			modem_ctl[4] = 0x40;
 			dev_dbg(dev, "%s - flow control = NONE\n", __func__);
 		}
 
-- 
1.8.4.5