From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: [PATCH v2 2/4] Documentation: Add documentation for APM X-Gene SoC PMU DTS binding Date: Mon, 2 May 2016 15:56:48 -0500 Message-ID: <20160502205648.GA7374@rob-hp-laptop> References: <1460510547-17611-1-git-send-email-ttnguyen@apm.com> <1460510547-17611-3-git-send-email-ttnguyen@apm.com> <20160418170009.GA15338@rob-hp-laptop> <20160420113121.GE2514@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20160420113121.GE2514@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Will Deacon Cc: Tai Tri Nguyen , Mark Rutland , catalin.marinas@arm.com, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel , patches List-Id: devicetree@vger.kernel.org On Wed, Apr 20, 2016 at 12:31:22PM +0100, Will Deacon wrote: > On Mon, Apr 18, 2016 at 01:04:53PM -0700, Tai Tri Nguyen wrote: > > >> +Required properties for MCB subnode: > > >> +- compatible : Shall be "apm,xgene-pmu-mcb". > > >> +- reg : First resource shall be the MCB PMU resource. > > >> +- index : Instance number of the MCB PMU. > > >> + > > >> +Required properties for MC subnode: > > >> +- compatible : Shall be "apm,xgene-pmu-mc". > > >> +- reg : First resource shall be the MC PMU resource. > > >> +- index : Instance number of the MC PMU. > > > > > > Don't use indexes. You probably need phandles to the nodes these are > > > related to. > > > > > > How many variations of child nodes do you expect to have? 2, 10, 50? You > > > might want to just collapse all this down to a single node and put this > > > information in the driver if it is fixed for each SoC and there's only a > > > handful. > > > > > > > For each kind of PMU, for example memory controller PMU, I expect to > > have the number of instances up to 8. > > They are actually all independent PMU nodes and have their own CSR memory bases. > > The indexes are used for exposing the devices to perf user only. It > > doesn't have an impact on the programming model. > > Mark also had the same concern. > > Regardless, I'll need an ack from Rob or Mark before I can merge this. I still have a concern with this. Needing an index to expose to the user is generally not a valid reason. That's OS specific and therefore doesn't belong in DT. Rob