This is a note to let you know that I've just added the patch titled

serial: 8250: Preserve DLD[7:4] for PORT_XR17V35X

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: serial-8250-preserve-dld-for-port_xr17v35x.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Wed Dec 6 16:43:17 CET 2017

From: Aaron Sierra asierra@xes-inc.com Date: Wed, 4 Oct 2017 10:01:28 -0500 Subject: serial: 8250: Preserve DLD[7:4] for PORT_XR17V35X

From: Aaron Sierra asierra@xes-inc.com

[ Upstream commit 0ab84da2e076948c49d36197ee7d254125c53eab ]

The upper four bits of the XR17V35x fractional divisor register (DLD) control general chip function (RS-485 direction pin polarity, multidrop mode, XON/XOFF parity check, and fast IR mode). Don't allow these bits to be clobbered when setting the baudrate.

Signed-off-by: Aaron Sierra asierra@xes-inc.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/serial/8250/8250_port.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2223,8 +2223,11 @@ static void serial8250_set_divisor(struc serial_dl_write(up, quot);

/* XR17V35x UARTs have an extra fractional divisor register (DLD) */ - if (up->port.type == PORT_XR17V35X) + if (up->port.type == PORT_XR17V35X) { + /* Preserve bits not related to baudrate; DLD[7:4]. */ + quot_frac |= serial_port_in(port, 0x2) & 0xf0; serial_port_out(port, 0x2, quot_frac); + } }

static unsigned int

Patches currently in stable-queue which might be from asierra@xes-inc.com are

queue-4.4/serial-8250-preserve-dld-for-port_xr17v35x.patch