From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolin Chen Subject: Re: [PATCH] dmaengine: imx-sdma: Add DMA event remapping for imx6sx-sdma Date: Mon, 20 Apr 2015 10:34:33 -0700 Message-ID: <20150420173433.GA6920@Asurada> References: <1429076351-4429-1-git-send-email-nicoleotsuka@gmail.com> <20150420094541.GL6325@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20150420094541.GL6325@pengutronix.de> Sender: linux-kernel-owner@vger.kernel.org To: Sascha Hauer Cc: vinod.koul@intel.com, fabio.estevam@freescale.com, b38343@freescale.com, robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, dan.j.williams@intel.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org List-Id: devicetree@vger.kernel.org Hi Sascha, Thank you for the comments. On Mon, Apr 20, 2015 at 11:45:41AM +0200, Sascha Hauer wrote: > On Tue, Apr 14, 2015 at 10:39:11PM -0700, Nicolin Chen wrote: > > The SDMA on imx6sx has a few DMA event remapping configurations > > inside the GPR (General Purpose Register) of that SoC. When users > > want to use a non-default DMA event, they need to configure the > > GPR register. So this patch gives an interface of the GPR and > > implements it in the SDMA driver so as to finish the DMA event > > remapping. > > > > Signed-off-by: Nicolin Chen > > diff --git a/Documentation/devicetree/bindings/dma/fsl-imx-sdma.txt b/Documentation/devicetree/bindings/dma/fsl-imx-sdma.txt > > index dc8d3aa..03315a6 100644 > > --- a/Documentation/devicetree/bindings/dma/fsl-imx-sdma.txt > > +++ b/Documentation/devicetree/bindings/dma/fsl-imx-sdma.txt > > @@ -8,6 +8,7 @@ Required properties: > > "fsl,imx51-sdma" > > "fsl,imx53-sdma" > > "fsl,imx6q-sdma" > > + "fsl,imx6sx-sdma" > > The -to variants should be preferred since they allow to determine the > > correct ROM script addresses needed for the driver to work without additional > > firmware. > > @@ -19,6 +20,14 @@ Required properties: > > - fsl,sdma-ram-script-name : Should contain the full path of SDMA RAM > > scripts firmware > > > > +Optional properties: > > +- fsl, sdma-event-remap : List of one or more DMA event remapping > > + configurations. Its format: <&gpr addr shift val> > > + gpr : the gpr phandle > > + addr : the register address of the GPR > > + shift : the bit shift of the GPR register > > + val : the value of that bit > > This binding allows arbitrary register writes to the GPR register space. > I don't think we want to allow that. A binding for this if necessary at > all must be higher level. I was actually wondering where could be the best place to put this in. But I couldn't figure out a better place than this driver while being worried about the violation as you mentioned. But what could be that higher level? Thank you Nicolin