Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753898AbdCOPjn (ORCPT ); Wed, 15 Mar 2017 11:39:43 -0400 Received: from esa1.microchip.iphmx.com ([68.232.147.91]:37156 "EHLO esa1.microchip.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751280AbdCOPjA (ORCPT ); Wed, 15 Mar 2017 11:39:00 -0400 X-Greylist: delayed 593 seconds by postgrey-1.27 at vger.kernel.org; Wed, 15 Mar 2017 11:39:00 EDT X-IronPort-AV: E=Sophos;i="5.36,169,1486450800"; d="scan'208";a="261386" From: Nicolas Ferre To: Richard Genoud , CC: , , Nicolas Ferre , "stable # 4 . 4+" Subject: [RFC PATCH] tty/serial: atmel: fix TX path in atmel_console_write() Date: Wed, 15 Mar 2017 16:29:48 +0100 Message-ID: <20170315152948.10978-1-nicolas.ferre@microchip.com> X-Mailer: git-send-email 2.9.0 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1435 Lines: 39 A side effect of 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA from transmitting in stop_tx") is that the console can be called with TX path disabled. Then the system would hang trying to push charecters out in atmel_console_putchar(). Signed-off-by: Nicolas Ferre Fixes: 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA from transmitting in stop_tx") Cc: stable # 4.4+ --- Hi Richard, I found this to fix the problem with system hang in my linux-4.4-at91 branch (in the atmel_console_putchar() waiting loop actually). I'm open to more insignt. As we cannot figure out if this bit is set or not, I didn't preserve the current status... Regards, drivers/tty/serial/atmel_serial.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index dcebb28ffbc4..7372dbdb7a4c 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -2483,6 +2483,9 @@ static void atmel_console_write(struct console *co, const char *s, u_int count) pdc_tx = atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN; atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS); + /* Make sure that tx path is actually able to send characters */ + atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN); + uart_console_write(port, s, count, atmel_console_putchar); /* -- 2.9.0