linux-kernel - [PATCH v2 1/3] USB: serial: cp210x: Fixed RTS mode setting by the CRTSCTS flag.

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Date:	Fri, 29 Apr 2016 21:22:08 -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 v2 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>
---
Changes in v2:
Improved CRTSCTS fix based on feedback. Dropped get_termios error handling.

 drivers/usb/serial/cp210x.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index dd47823..abcdb63 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -163,10 +163,6 @@ static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(0x1843, 0x0200) }, /* Vaisala USB Instrument Cable */
 	{ USB_DEVICE(0x18EF, 0xE00F) }, /* ELV USB-I2C-Interface */
 	{ USB_DEVICE(0x18EF, 0xE025) }, /* ELV Marble Sound Board 1 */
-	{ USB_DEVICE(0x1901, 0x0190) }, /* GE B850 CP2105 Recorder interface */
-	{ USB_DEVICE(0x1901, 0x0193) }, /* GE B650 CP2104 PMC interface */
-	{ USB_DEVICE(0x1901, 0x0194) },	/* GE Healthcare Remote Alarm Box */
-	{ USB_DEVICE(0x19CF, 0x3000) }, /* Parrot NMEA GPS Flight Recorder */
 	{ USB_DEVICE(0x1ADB, 0x0001) }, /* Schweitzer Engineering C662 Cable */
 	{ USB_DEVICE(0x1B1C, 0x1C00) }, /* Corsair USB Dongle */
 	{ USB_DEVICE(0x1BA4, 0x0002) },	/* Silicon Labs 358x factory default */
@@ -967,8 +963,7 @@ 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