From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lauri Hintsala Subject: Re: [PATCH v2 2/3] serial: mxs-auart: add the DMA support for mx28 Date: Thu, 15 Nov 2012 09:22:39 +0200 Message-ID: <50A4983F.8080407@bluegiga.com> References: <1351074456-25863-1-git-send-email-b32955@freescale.com> <1351074456-25863-3-git-send-email-b32955@freescale.com> <50A21613.6030709@bluegiga.com> <50A45F83.1010009@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from bluegiga.fi ([194.100.31.45]:57333 "EHLO darkblue.bluegiga.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2992753Ab2KOHWl (ORCPT ); Thu, 15 Nov 2012 02:22:41 -0500 In-Reply-To: <50A45F83.1010009@freescale.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Huang Shijie Cc: gregkh@linuxfoundation.org, alan@linux.intel.com, linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, shawn.guo@linaro.org, linux@arm.linux.org.uk, vinod.koul@intel.com, Veli-Pekka Peltola , Fabio Estevam Hi, On 11/15/2012 05:20 AM, Huang Shijie wrote: > =E4=BA=8E 2012=E5=B9=B411=E6=9C=8813=E6=97=A5 17:42, Lauri Hintsala =E5= =86=99=E9=81=93: >> Hi Huang, >> >> DMA support doesn't work with latest stable v3.6.5 or development >> 3.7-rc5 kernels. I get following error message when I open the seria= l >> port /dev/ttyAPP0: >> >> [ 48.730000] mxs-auart 8006a000.serial: step 1 error >> [ 48.750000] mxs-auart 8006a000.serial: We can not start up the DMA. >> > I tested this patch set in imx28-evk board Rev C with linux-next-2012= 1114. > it works fine. > > Maybe you can try the linux-next code. I tested linux-next-20121114 on apx4devkit (imx28 based device) and I=20 got the same error message: # stty -F /dev/ttyAPP0 crtscts; microcom /dev/ttyAPP0 -s 115200 [ 133.710000] mxs-auart 8006a000.serial: step 1 error [ 133.720000] mxs-auart 8006a000.serial: We can not start up the DMA. > About the flow control: > If we do not enable the HW flow control, the data may lost. And I do = not > know how to handle with the Xon/Xoff when the DMA is supported. I do not have the answer but it is already implemented in Freescale's=20 reference kernel=20 (http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/tree/drive= rs/serial/mxs-auart.c?h=3Dimx_2.6.35_11.09.01).=20 So I think it is possible to handle all data without HW flow control. Best Regards, Lauri Hintsala -- To unsubscribe from this list: send the line "unsubscribe linux-serial"= in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: lauri.hintsala@bluegiga.com (Lauri Hintsala) Date: Thu, 15 Nov 2012 09:22:39 +0200 Subject: [PATCH v2 2/3] serial: mxs-auart: add the DMA support for mx28 In-Reply-To: <50A45F83.1010009@freescale.com> References: <1351074456-25863-1-git-send-email-b32955@freescale.com> <1351074456-25863-3-git-send-email-b32955@freescale.com> <50A21613.6030709@bluegiga.com> <50A45F83.1010009@freescale.com> Message-ID: <50A4983F.8080407@bluegiga.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On 11/15/2012 05:20 AM, Huang Shijie wrote: > ? 2012?11?13? 17:42, Lauri Hintsala ??: >> Hi Huang, >> >> DMA support doesn't work with latest stable v3.6.5 or development >> 3.7-rc5 kernels. I get following error message when I open the serial >> port /dev/ttyAPP0: >> >> [ 48.730000] mxs-auart 8006a000.serial: step 1 error >> [ 48.750000] mxs-auart 8006a000.serial: We can not start up the DMA. >> > I tested this patch set in imx28-evk board Rev C with linux-next-20121114. > it works fine. > > Maybe you can try the linux-next code. I tested linux-next-20121114 on apx4devkit (imx28 based device) and I got the same error message: # stty -F /dev/ttyAPP0 crtscts; microcom /dev/ttyAPP0 -s 115200 [ 133.710000] mxs-auart 8006a000.serial: step 1 error [ 133.720000] mxs-auart 8006a000.serial: We can not start up the DMA. > About the flow control: > If we do not enable the HW flow control, the data may lost. And I do not > know how to handle with the Xon/Xoff when the DMA is supported. I do not have the answer but it is already implemented in Freescale's reference kernel (http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/tree/drivers/serial/mxs-auart.c?h=imx_2.6.35_11.09.01). So I think it is possible to handle all data without HW flow control. Best Regards, Lauri Hintsala