From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vinod Koul Subject: Re: [PATCH 2/2] dma: xilinx: dpdma: Add the Xilinx DisplayPort DMA engine driver Date: Mon, 29 Jan 2018 09:49:35 +0530 Message-ID: <20180129041927.GJ18649@localhost> References: <1515204848-3493-1-git-send-email-hyun.kwon@xilinx.com> <1515204848-3493-2-git-send-email-hyun.kwon@xilinx.com> <20180112141355.GO18649@localhost> <20180124144059.GI18649@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Hyun Kwon Cc: "dmaengine-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Michal Simek , Tejas Upadhyay List-Id: devicetree@vger.kernel.org On Wed, Jan 24, 2018 at 05:45:00PM +0000, Hyun Kwon wrote: > > > > > +static int xilinx_dpdma_config(struct dma_chan *dchan, > > > > > + struct dma_slave_config *config) > > > > > +{ > > > > > + if (config->direction != DMA_MEM_TO_DEV) > > > > > + return -EINVAL; > > > > > > > > ?? Why are the config values not used, how else do you configure the > > > > channel? > > > > > > > > > > There's not much configuration to be done. Channels are pretty much > > identical > > > with fixed configurations. > > > > hmmm, you do support DMA_SLAVE right? > > > > Yes, and it's single direction, DMA_MEM_TO_DEV. Okay how do you find the DMA data width and the burst to apply when you DMA to device? Are these not programmable? I think you need to go back and check that part. Moreover a client may send you parameters and program the Device FIFO, you not honoring those will result in bad data received on Device, am sure you don't want that -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html