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;a=summary
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@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Wed Dec 6 16:43:17 CET 2017
From: Aaron Sierra <asierra@xxxxxxxxxxx>
Date: Wed, 4 Oct 2017 10:01:28 -0500
Subject: serial: 8250: Preserve DLD[7:4] for PORT_XR17V35X
From: Aaron Sierra <asierra@xxxxxxxxxxx>
[ 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@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxxxx are
queue-4.4/serial-8250-preserve-dld-for-port_xr17v35x.patch