[PATCH 4.6 044/100] USB: serial: cp210x: fix hardware flow-control disable

Greg Kroah-Hartman
2016-05-30T21:22:29Z

From: Konstantin Shkolnyy <konstantin.shkolnyy@gmail.com>

commit a377f9e906af4df9071ba8ddba60188cb4013d93 upstream.

A bug in the CRTSCTS handling caused RTS to alternate between

CRTSCTS=0 => "RTS is transmit active signal" and
CRTSCTS=1 => "RTS is used for receive flow control"

instead of

CRTSCTS=0 => "RTS is statically active" and
CRTSCTS=1 => "RTS is used for receive flow control"

This only happened after first having enabled CRTSCTS.

Signed-off-by: Konstantin Shkolnyy <konstantin.shkolnyy@gmail.com>
Fixes: 39a66b8d22a3 ("[PATCH] USB: CP2101 Add support for flow control")
[johan: reword commit message ]
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -971,8 +971,7 @@ static void cp210x_set_termios(struct tt
} 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__);
}