linux-kernel - [PATCH v4 1/3] USB: serial: cp210x: Fixed RTS mode setting by the CRTSCTS flag.

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Date:	Tue,  3 May 2016 19:52:08 -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 v4 1/3] USB: serial: cp210x: Fixed RTS mode setting by the CRTSCTS flag.

A bug in the CRTSCTS 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"
This only happened after first having enabled CRTSCTS.

Signed-off-by: Konstantin Shkolnyy <konstantin.shkolnyy@...il.com>
---
v4:
Same series of patches, fixed names and defines by feedback.
v3:
Regenerated the patches correctly against the latest usb-next branch.
v2
Improved CRTSCTS fix by feedback. Dropped get_termios error handling fix.

 drivers/usb/serial/cp210x.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index dd47823..fef7a51 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -967,8 +967,7 @@ static void cp210x_set_termios(struct tty_struct *tty,
 		} 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