From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: PMU node location Date: Sat, 19 Jan 2013 10:35:50 -0600 Message-ID: <50FACB66.30805@gmail.com> References: <50EEC672.5050405@monstr.eu> <50F18742.5070501@gmail.com> <50F225AC.6030407@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <50F225AC.6030407-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Stephen Warren Cc: devicetree-discuss , Peter Crosthwaite , Soren Brinkmann List-Id: devicetree@vger.kernel.org On 01/12/2013 09:10 PM, Stephen Warren wrote: > On 01/12/2013 08:54 AM, Rob Herring wrote: >> On 01/10/2013 07:47 AM, Michal Simek wrote: >>> Hi Rob, Mark, Grant and others, >>> >>> I want to check with you the location of ARM pmu node >>> I see that >>> 1) highbank and dbx5x0 have it in soc node >>> >>> 2) vexpress and tegra have no main bus and pmu is in root like all >>> others devices. >>> (Any reason no to have main bus? Does it mean that there is no bus or >>> that all >>> devices are accessible?) >> >> That seems really wrong in general. Any memory mapped device is on a bus >> of some kind. I'm not sure the reasoning. Perhaps Stephen can explain. > > I saw no need to have add a bus node (there wasn't one before I started > touching DT on Tegra); the top-level of the DT represents the CPU's > entire view of the address space and has #address-cells/#size-cells, so > devices get probed there just fine, whether they're addressed MMIO > devices or not. The top level doesn't really represent a bus. It is basically all the things that have no hierarchical relationship (cpu, memory, chosen, peripheral buses). The reason to have a bus node is to define "simple-bus" While I would do it differently, I don't recommend changing it at this point. Although, this could be changed without compatibility issues. Rob