From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753297AbaIPJmS (ORCPT ); Tue, 16 Sep 2014 05:42:18 -0400 Received: from h1446028.stratoserver.net ([85.214.92.142]:49522 "EHLO mail.ahsoftware.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752709AbaIPJmP (ORCPT ); Tue, 16 Sep 2014 05:42:15 -0400 Message-ID: <541805E3.6080003@ahsoftware.de> Date: Tue, 16 Sep 2014 11:41:55 +0200 From: Alexander Holler User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 MIME-Version: 1.0 To: Robin Gong CC: shawn.guo@freescale.com, kernel@pengutronix.de, robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, linux@arm.linux.org.uk, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, fugang.duan@freescale.com Subject: Re: [PATCH v2] ARM: dts: imx6dl: disable dma support for spi on i.mx6dl References: <1410327012-31185-1-git-send-email-b38343@freescale.com> <5416D26A.4080707@ahsoftware.de> <20140916035204.GB20800@Robin-OptiPlex-780> In-Reply-To: <20140916035204.GB20800@Robin-OptiPlex-780> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 16.09.2014 05:52, schrieb Robin Gong: > On Mon, Sep 15, 2014 at 01:50:02PM +0200, Alexander Holler wrote: >> Am 10.09.2014 07:30, schrieb Robin Gong: >>> There is one weird data in rxfifo after one full rx/tx transfer >>> done sometimes. It looks a design issue and hard to workaround >>> totally, so disable dma functhion here. And will re-enable it >>> once the root cause found. >> >> Hmm, I experience problems with DMA too but on uart3. I'm using the same >> workaround for the uart (I've just commented out the dma entries in the DT). >> The problem manifests itself here such, that brcm_patchram_plus >> hangs while uploading the firmware to a BCM4330 connected at uart3 >> (reproducible). >> >> So maybe there is a bug in the DMA-engine which not only effects >> SPI. Or both drivers contain the same error in handling DMA (maybe >> through c&p). >> But that's just specualtion from me, I haven't looked further into >> that problem. >> >> Regards, >> >> Alexander Holler > Thanks for your information share. But my issue should be caused by hardware, > since everything is ok if it runs on other i.mx6 chip. Is your board also based > on i.mx6 chip? If yes, hope you can raise your issue in freescale community or > contact with Andy whose mail address added in CC list fugang.duan@freescale.cm. > We have fix some bugs in UART DMA case. It's an i.mx6q (Wandboard quad c1) where I have this problem with mainline and much older (but heavily patched freescale 3.10.x based) kernels. A quick web-search suggests that this problem exists since a long time (noticed mainly by people which try to use BT as this seems to be the major use case for high speed serial communication). Regards, Alexander Holler