From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751944AbcF1E2I (ORCPT ); Tue, 28 Jun 2016 00:28:08 -0400 Received: from mga04.intel.com ([192.55.52.120]:63069 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750871AbcF1E2G (ORCPT ); Tue, 28 Jun 2016 00:28:06 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.26,539,1459839600"; d="scan'208";a="984556702" Date: Tue, 28 Jun 2016 10:04:59 +0530 From: Vinod Koul To: Appana Durga Kedareswara Rao Cc: "robh+dt@kernel.org" , "pawel.moll@arm.com" , "mark.rutland@arm.com" , "ijc+devicetree@hellion.org.uk" , "galak@codeaurora.org" , Michal Simek , Soren Brinkmann , "dan.j.williams@intel.com" , "moritz.fischer@ettus.com" , "laurent.pinchart@ideasonboard.com" , "luis@debethencourt.com" , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "dmaengine@vger.kernel.org" Subject: Re: [PATCH 2/4] dmaengine: vdma: Add support for mulit-channel dma mode Message-ID: <20160628043459.GR22564@localhost> References: <1465549954-30220-1-git-send-email-appanad@xilinx.com> <1465549954-30220-3-git-send-email-appanad@xilinx.com> <20160621155502.GB16910@localhost> <20160621163340.GE16910@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 22, 2016 at 07:04:28AM +0000, Appana Durga Kedareswara Rao wrote: > > > > > > > > Can you elobrate what you meant by Multichannel mode? This patch > > > > seems to do two things, one is to add interleaved dma support and > > > > something else. Can you explain the latter part? > > > > > > AXI DMA has two Stream interfaces (Memory to Stream MM2S and Stream to > > > Memory S2MM) > > > > what is a stream in this context? > > Stream means I/O transfer (Memory to I/O and I/O to Memory). > Sorry if I confused you. > > > > > > In Multi-Channel dma mode each stream interface can be configured up to 16 > > channels. > > > In Multi-channel DMA mode IP supports only interleaved transfers (2-D > > transfers). > > > > > > > > > > > > > > > > /** > > > > > + * struct xilinx_mcdma_config - DMA Multi channel configuration > > > > > +structure > > > > > + * @tdest: Channel to operate on > > > > > + * @tid: Channel configuration > > > > > + * @tuser: Tuser configuration > > > > > + * @ax_user: ax_user value > > > > > + * @ax_cache: ax_cache value > > > > > + */ > > > > > +struct xilinx_mcdma_config { > > > > > + u8 tdest; > > > > > + u8 tid; > > > > > + u8 tuser; > > > > > + u8 ax_user; > > > > > + u8 ax_cache; > > > > > > > > can you describe these in details, what do these do, what are the > > > > values to be programmed? > > > > > > As said above In Multi-Channel Mode each Stream interface can be > > > Configured up to 16 channels each channel is differentiated based on the tdest > > and tid values. > > > > Then why are you not registering 16 channels for this? That should give you > > channel to operate on! > > The number of channels are configurable. > We are registering number of Channels that h/w configured for. > > Will fix in the next version. Will remove this config. > And based on the channel type will configure the h/w. Looking at this you should redesign! The vchan was designed to operate on 'virtual' channels. The hardware channels can be independent of that. Your IP seems to be a good fit for that approach. Do not link the two and separate them. User can have a virtual channel. In your driver, you can manage hardware channels... > > > > > > > > > tdest: > > > TDEST provides routing information for the data stream. > > > > pls elobrate > > Need to configure this with the channel number that > We would like to transfer data. This should be internal to driver... -- ~Vinod