From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sylwester Nawrocki Subject: Re: [PATCH 1/1] serial: samsung: Clear operation mode on UART shutdown Date: Fri, 20 Mar 2015 14:34:41 +0100 Message-ID: <550C21F1.5030404@samsung.com> References: <1426246731-13751-1-git-send-email-javier.martinez@collabora.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout1.w1.samsung.com ([210.118.77.11]:19655 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751222AbbCTNes (ORCPT ); Fri, 20 Mar 2015 09:34:48 -0400 In-reply-to: <1426246731-13751-1-git-send-email-javier.martinez@collabora.co.uk> Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Javier Martinez Canillas , Robert Baldyga Cc: Greg Kroah-Hartman , Jiri Slaby , Olof Johansson , Doug Anderson , linux-samsung-soc@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org On 13/03/15 12:38, 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; > } The patch looks good to me, Robert could you comment on that? Reviewed-by: Sylwester Nawrocki -- Thanks, Sylwester