Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751669AbaATIAT (ORCPT ); Mon, 20 Jan 2014 03:00:19 -0500 Received: from mail-lb0-f177.google.com ([209.85.217.177]:63399 "EHLO mail-lb0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750726AbaATIAQ (ORCPT ); Mon, 20 Jan 2014 03:00:16 -0500 MIME-Version: 1.0 In-Reply-To: <201401171713.08550.arnd@arndb.de> References: <1389894803-4147-1-git-send-email-sthokal@xilinx.com> <1389894803-4147-2-git-send-email-sthokal@xilinx.com> <201401171713.08550.arnd@arndb.de> Date: Mon, 20 Jan 2014 13:30:14 +0530 X-Google-Sender-Auth: oJBBEi2_OONrQK3kc1n8xqeGy_s Message-ID: Subject: Re: [PATCH] dma: Add Xilinx AXI Video Direct Memory Access Engine driver support From: Srikanth Thokala To: Arnd Bergmann Cc: linux-arm-kernel@lists.infradead.org, Srikanth Thokala , dan.j.williams@intel.com, vinod.koul@intel.com, michal.simek@xilinx.com, Grant Likely , robh+dt@kernel.org, dmaengine@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Arnd, On Fri, Jan 17, 2014 at 9:43 PM, Arnd Bergmann wrote: > On Thursday 16 January 2014, Srikanth Thokala wrote: >> @@ -0,0 +1,71 @@ >> +Xilinx AXI VDMA engine, it does transfers between memory and video devices. >> +It can be configured to have one channel or two channels. If configured >> +as two channels, one is to transmit to the video device and another is >> +to receive from the video device. >> + >> +Required properties: >> +- compatible: Should be "xlnx,axi-vdma-1.00.a" >> +- #dma-cells: Should be <1>, see "dmas" property below >> +- reg: Should contain VDMA registers location and length. >> +- interrupts: Should contain per channel VDMA interrupts. >> +- compatible (child node): It should be either "xlnx,axi-vdma-mm2s-channel" or >> + "xlnx,axi-vdma-s2mm-channel". It depends on the hardware design and it >> + can also have both channels. >> +- xlnx,device-id: Should contain device number in each channel. It should be >> + {0,1,2...so on} to the number of VDMA devices configured in hardware. >> +- xlnx,num-fstores: Should be the number of framebuffers as configured in h/w. >> +- xlnx,data-width: Should contain the stream data width, takes {32,64...so on}. >> +- xlnx,flush-fsync: (Optional) Tells whether which channel to Flush on Fsync. >> + It takes following values: >> + {1}, flush both channels >> + {2}, flush mm2s channel >> + {3}, flush s2mm channel >> +- xlnx,include-sg: (Optional) Tells whether configured for Scatter-mode in >> + the hardware. >> +- xlnx,include-dre: (Optional) Tells whether hardware is configured for Data >> + Realignment Engine. >> +- xlnx,genlock-mode: (Optional) Tells whether Genlock synchornisation is >> + enabled/disabled in hardware. > > The documentation doesn't seem to match the example, since you don't mention > the fact that the channels have separate nodes here, or which properties > are meant for the parent or the child node. Also, some of the "required" > properties are absent in the example, which makes no sense. > I will fix this ambiguity in my v2. > I also assume that some of the properties should just go away: > > * xlnx,device-id should be the argument in the handle from the slave device We can have multiple instances of this VDMA IP configured in the FPGA and we need a unique identifier for each VDMA device that is present in the FPGA. This device-id dt parameter forms the filter mask for the slave devices. As an example, this can be used to get a channel of specific VDMA device (assuming multiple instances) using the API dma_request_channel(). Please note this is an example of a slave device that doesnt have dt node. > * data width should be a property of the slave driver that is configured > through dma_slave_config(), unless you can have dma engines that only > support certain a width. Yes, this VDMA engine soft IP support only certain widths, which is configurable during IP synthesis. Srikanth > > Arnd > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/