From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754709AbdJINzI (ORCPT ); Mon, 9 Oct 2017 09:55:08 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41911 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754238AbdJIMo6 (ORCPT ); Mon, 9 Oct 2017 08:44:58 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Chanwoo Choi" , "Greg Kroah-Hartman" , "Marek Szyprowski" Date: Mon, 09 Oct 2017 13:44:25 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 164/192] serial: samsung: Reorder the sequence of clock control when call s3c24xx_serial_set_termios() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.49-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Chanwoo Choi commit b8995f527aac143e83d3900ff39357651ea4e0f6 upstream. This patch fixes the broken serial log when changing the clock source of uart device. Before disabling the original clock source, this patch enables the new clock source to protect the clock off state for a split second. Signed-off-by: Chanwoo Choi Reviewed-by: Marek Szyprowski Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/tty/serial/samsung.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/tty/serial/samsung.c +++ b/drivers/tty/serial/samsung.c @@ -757,6 +757,8 @@ static void s3c24xx_serial_set_termios(s /* check to see if we need to change clock source */ if (ourport->baudclk != clk) { + clk_prepare_enable(clk); + s3c24xx_serial_setsource(port, clk_sel); if (!IS_ERR(ourport->baudclk)) { @@ -764,8 +766,6 @@ static void s3c24xx_serial_set_termios(s ourport->baudclk = ERR_PTR(-EINVAL); } - clk_prepare_enable(clk); - ourport->baudclk = clk; ourport->baudclk_rate = clk ? clk_get_rate(clk) : 0; }