From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753390AbdKVWeV (ORCPT ); Wed, 22 Nov 2017 17:34:21 -0500 Received: from omzsmtpe01.verizonbusiness.com ([199.249.25.210]:47972 "EHLO omzsmtpe01.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753306AbdKVW2g (ORCPT ); Wed, 22 Nov 2017 17:28:36 -0500 From: alexander.levin@verizon.com Cc: Aaron Sierra , Greg Kroah-Hartman , alexander.levin@verizon.com X-Host: pioneer.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 4.4 09/16] serial: 8250: Preserve DLD[7:4] for PORT_XR17V35X Thread-Topic: [PATCH AUTOSEL for 4.4 09/16] serial: 8250: Preserve DLD[7:4] for PORT_XR17V35X Thread-Index: AQHTY+D1MNfB+km8ykOJ5zX/QjIU1g== Date: Wed, 22 Nov 2017 22:26:36 +0000 Message-ID: <20171122222628.20198-9-alexander.levin@verizon.com> References: <20171122222628.20198-1-alexander.levin@verizon.com> In-Reply-To: <20171122222628.20198-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vAMMYQZL025674 From: Aaron Sierra [ 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 Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/8250/8250_port.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) 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 -- 2.11.0