From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH] dma: Add Xilinx AXI Video Direct Memory Access Engine driver support Date: Mon, 20 Jan 2014 19:41:07 +0100 Message-ID: <201401201941.07633.arnd@arndb.de> References: <1389894803-4147-1-git-send-email-sthokal@xilinx.com> <201401201239.47665.arnd@arndb.de> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Srikanth Thokala Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, vinod.koul-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, michal.simek-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org, Grant Likely , robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, dmaengine-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On Monday 20 January 2014, Srikanth Thokala wrote: > > > >> > * 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. > > > > But what is this property used for in that case? Surely you can't > > connect a slave device to a dmaengine if the bus width doesn't match. > > You probably have a point here, but I don't understand it yet. > > There is a Data-Realignment Engine (DRE) in the IP which is only available for > data width setting of 64-bits and less. So, we use the data-width DT parameter > to verify this condition and we update alignment shift accordingly. Ok, I have to admit I didn't understand all of that, but you clearly know what you are talking about here, so I assume you are correct. Arnd -- 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