diff options
| author | Aaron Sierra <asierra@xes-inc.com> | 2017-10-04 10:01:28 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-12-09 18:42:40 +0100 |
| commit | ecd996c24a790b3c30346e45076b55ded497f207 (patch) | |
| tree | cb86f76175e5d5a546643a298eceb7075582d743 /drivers/tty | |
| parent | 86b9d66d1f3f4121853f46452d0a756217a55ea0 (diff) | |
serial: 8250: Preserve DLD[7:4] for PORT_XR17V35X
[ 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>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/8250/8250_port.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 56ccbcefdd85..d42d66b72d5a 100644 --- 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(struct uart_port *port, unsigned int baud, 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 |