From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Gong Subject: Re: [PATCH v2] ARM: dts: imx6dl: disable dma support for spi on i.mx6dl Date: Wed, 17 Sep 2014 16:51:08 +0800 Message-ID: <20140917085106.GB6369@Robin-OptiPlex-780> References: <1410327012-31185-1-git-send-email-b38343@freescale.com> <5416D26A.4080707@ahsoftware.de> <20140916035204.GB20800@Robin-OptiPlex-780> <541805E3.6080003@ahsoftware.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: <541805E3.6080003@ahsoftware.de> Sender: linux-kernel-owner@vger.kernel.org To: Alexander Holler 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 List-Id: devicetree@vger.kernel.org On Tue, Sep 16, 2014 at 11:41:55AM +0200, Alexander Holler wrote: > 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 Yes, we just have fixed the BT issue over high speed UART last month. Suggest you trying our patches based on v3.10.