From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751661AbdBYQfI (ORCPT ); Sat, 25 Feb 2017 11:35:08 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:33686 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751231AbdBYQfG (ORCPT ); Sat, 25 Feb 2017 11:35:06 -0500 Date: Sat, 25 Feb 2017 18:34:59 +0200 From: Krzysztof Kozlowski To: Tobias Jakobi Cc: Greg Kroah-Hartman , Jiri Slaby , Marek Szyprowski , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] serial: samsung: Continue to work if DMA request fails Message-ID: <20170225163459.o7uvvowmimsjkmb2@kozik-lap> References: <20170225162442.31848-1-krzk@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.6.2-neo (2016-08-21) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Feb 25, 2017 at 05:28:41PM +0100, Tobias Jakobi wrote: > Hello Krzysztof, > > Krzysztof Kozlowski wrote: > > If DMA is not available (even when configured in DeviceTree), the driver > > will fail the startup procedure thus making serial console not > > available. > > > > For example this causes boot failure on QEMU ARMv7 (Exynos4210, SMDKC210): > > [ 1.302575] OF: amba_device_add() failed (-19) for /amba/pdma@12680000 > > ... > > [ 11.435732] samsung-uart 13800000.serial: DMA request failed > > [ 72.963893] samsung-uart 13800000.serial: DMA request failed > > [ 73.143361] Kernel panic - not syncing: Attempted to kill init! exitcode=00000000 > > > > DMA is not necessary for serial to work, so continue with UART startup > > after emitting a warning. > > > > Fixes: Fixes: 62c37eedb74c ("serial: samsung: add dma reqest/release functions") > > Cc: > > Signed-off-by: Krzysztof Kozlowski > > --- > > drivers/tty/serial/samsung.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c > > index b4f86c219db1..7a17aedbf902 100644 > > --- a/drivers/tty/serial/samsung.c > > +++ b/drivers/tty/serial/samsung.c > > @@ -1031,8 +1031,10 @@ static int s3c64xx_serial_startup(struct uart_port *port) > > if (ourport->dma) { > > ret =3c24xx_serial_request_dma(ourport); > > if (ret < 0) { > > - dev_warn(port->dev, "DMA request failed\n"); > > - return ret; > > + dev_warn(port->dev, > > + "DMA request failed, DMA will not be used\n"); > > + devm_kfree(port->dev, ourport->dma); > > + ourport->dma =ULL; > This line looks odd. Did you want to assign NULL here? > Also, whitespace on both sides of '='? Ugh, I must ate it by mistake somehow because my git contains proper "NULL" here. Thanks for pointing this, I'll resend v3. Best regards, Krzysztof