From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v2] of/fdt: Allow memory node and root to have different size/address cells Date: Thu, 01 Oct 2015 14:21:59 +0200 Message-ID: <1712345.yOlLsP4Oji@wuerfel> References: <1443701901-362-1-git-send-email-vgupta@synopsys.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <1443701901-362-1-git-send-email-vgupta@synopsys.com> Sender: linux-arch-owner@vger.kernel.org To: Vineet Gupta Cc: Rob Herring , kbuild test robot , "kbuild-all@01.org" , Grant Likely , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org List-Id: devicetree@vger.kernel.org On Thursday 01 October 2015 17:48:21 Vineet Gupta wrote: > Currently memory node parsing uses root "#size-cells", "#address-cells" > This doesn't work correctly when memory address/size is different or > greater than root's. > > e.g. ARC 32-bit systems implementing physical adressing extension and > say 4GB of memory. All peripherals mappings stay within the 4GB (so root > address/size cells remain 1 each), only the memory node address/size > cells needs to specify greater than 32-bits as below > > memory { > device_type = "memory"; > reg = <0x0 0x80000000 0x1 0x00000000>; /* 4 GB */ > #address-cells = <2>; > #size-cells = <2>; > }; > > This patch lets me boot a ARC system with PAE40 + 4GB of memory specified > as above and fails to boot otherwise as memory parsing doesn't populate > right base, size. > This looks wrong: the #address-cells property in a device node is used to parse the reg property of its child nodes, not the node itself. The only way to list memory like this is to put #size-cells=<2> into the root node. All lower bus nodes can then use the normal #address-cells/#size-cells again and use a ranges property to convert the register ranges so you don't need to update all nodes. Arnd