From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751267AbbCTMTz (ORCPT ); Fri, 20 Mar 2015 08:19:55 -0400 Received: from bhuna.collabora.co.uk ([93.93.135.160]:57860 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750852AbbCTMTw (ORCPT ); Fri, 20 Mar 2015 08:19:52 -0400 Message-ID: <550C1060.1040900@collabora.co.uk> Date: Fri, 20 Mar 2015 13:19:44 +0100 From: Javier Martinez Canillas User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.2.0 MIME-Version: 1.0 To: Greg Kroah-Hartman CC: Jiri Slaby , Robert Baldyga , Sylwester Nawrocki , Olof Johansson , Doug Anderson , linux-samsung-soc@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] serial: samsung: Clear operation mode on UART shutdown References: <1426246731-13751-1-git-send-email-javier.martinez@collabora.co.uk> In-Reply-To: <1426246731-13751-1-git-send-email-javier.martinez@collabora.co.uk> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On 03/13/2015 12:38 PM, Javier Martinez Canillas wrote: > Exynos serial ports operate either in a DMA-based or interrupt-based > modes. In DMA-based mode, the UART generates a transfer data request > and a Transmission (Tx) interrupt in interrupt-based mode. > > The Tx IRQ is only unmasked in interrupt-based mode and it was done > in s3c24xx_serial_start_tx(). Commit ba019a3e2ad5 ("serial: samsung: > remove redundant interrupt enabling") removed the IRQ enable on that > function since it is enabled when the mode is set in enable_tx_pio(). > > The problem is that enable_tx_pio() is only called if the port mode > has not been set before but the mode was not cleared on .shutdown(). > > So if the UART was shutdown and then started up again, the mode set > will remain and the Tx IRQ won't be unmasked. > > This caused a hang on at least Exynos5250, Exynos5420 and Exynos5800 > when the system is rebooted or powered off. > > Fixes: ba019a3e2ad5 ("serial: samsung: remove redundant interrupt enabling") > Signed-off-by: Javier Martinez Canillas > --- > > I noticed this issue on an Exynos5250 Snow, Exynos5420 Peach Pit and Exynos > 5800 Peach Pi Chromebooks. This patch fixes the issue on all of them. > > The offending commit landed in v4.0-rc1 so this fix is -rc material. > > drivers/tty/serial/samsung.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c > index af821a908720..cf08876922f1 100644 > --- a/drivers/tty/serial/samsung.c > +++ b/drivers/tty/serial/samsung.c > @@ -963,6 +963,7 @@ static void s3c24xx_serial_shutdown(struct uart_port *port) > free_irq(ourport->tx_irq, ourport); > tx_enabled(port) = 0; > ourport->tx_claimed = 0; > + ourport->tx_mode = 0; > } > > if (ourport->rx_claimed) { > Any comments about this patch? 3.14-rc5 will most likely be released this weekend so we are running out of time to fix this issue before 3.14 is released. Best regards, Javier