From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from co9outboundpool.messaging.microsoft.com (co9ehsobe003.messaging.microsoft.com [207.46.163.26]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "MSIT Machine Auth CA 2" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 952512C00E8 for ; Tue, 17 Sep 2013 08:46:43 +1000 (EST) Message-ID: <1379371590.2536.187.camel@snotra.buserror.net> Subject: Re: [PATCH v9 2/3] DMA: Freescale: Add new 8-channel DMA engine device tree nodes From: Scott Wood To: Mark Rutland Date: Mon, 16 Sep 2013 17:46:30 -0500 In-Reply-To: <20130912171541.GH22013@e106331-lin.cambridge.arm.com> References: <1377861980-7027-1-git-send-email-hongbo.zhang@freescale.com> <1377861980-7027-3-git-send-email-hongbo.zhang@freescale.com> <20130902155636.GA18206@e106331-lin.cambridge.arm.com> <5225A57E.4030003@freescale.com> <20130912171541.GH22013@e106331-lin.cambridge.arm.com> Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Cc: "devicetree@vger.kernel.org" , "ian.campbell@citrix.com" , Pawel Moll , "swarren@wwwdotorg.org" , Hongbo Zhang , "linux-kernel@vger.kernel.org" , "rob.herring@calxeda.com" , "vinod.koul@intel.com" , "djbw@fb.com" , "linuxppc-dev@lists.ozlabs.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2013-09-12 at 18:15 +0100, Mark Rutland wrote: > On Tue, Sep 03, 2013 at 10:01:50AM +0100, Hongbo Zhang wrote: > > On 09/02/2013 11:58 PM, Mark Rutland wrote: > > > May some channels be unusable for some reason, or will all eight > > > channels be wired on any given Elo3 DMA? > > Sorry, not get your point clearly, maybe you are clear now because of my > > previous explanations. > > I assume that on any El03 DMA, there won't be a case where you can't > describe the channel at 0x80, for instance. It will always be present > (but it might not be wired up to anything any therefore be useful)? > > This was related to my concerns about the status register description -- > if the channels at 0x0,0x80,0x100,0x180 weren't wired, what would get > described in the dt? I guess that would never actually happen because > all 8 channels must always be present in the Elo3 IP block. If a channel is not usable for whatever reason (other than that "used for a different fixed purpose and thus described with a different compatible" thing that was mentioned earlier in these threads), wouldn't it just have status = "disabled" or similar, or be absent? -Scott