Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753396AbaBYUsq (ORCPT ); Tue, 25 Feb 2014 15:48:46 -0500 Received: from smtp.codeaurora.org ([198.145.11.231]:44230 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752844AbaBYUsn convert rfc822-to-8bit (ORCPT ); Tue, 25 Feb 2014 15:48:43 -0500 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.1 \(1827\)) Subject: Re: [PATCH v5 2/4] devicetree: bindings: Document Krait CPU/L1 EDAC From: Kumar Gala In-Reply-To: <20140225111655.GA6855@e102568-lin.cambridge.arm.com> Date: Tue, 25 Feb 2014 14:48:38 -0600 Cc: Stephen Boyd , Borislav Petkov , "linux-kernel@vger.kernel.org" , "linux-arm-msm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-edac@vger.kernel.org" , Mark Rutland , "devicetree@vger.kernel.org" Content-Transfer-Encoding: 8BIT Message-Id: References: <1389735034-21430-3-git-send-email-sboyd@codeaurora.org> <20140115102701.GA27314@e102568-lin.cambridge.arm.com> <20140115165623.GJ14405@codeaurora.org> <20140116013840.GA674@codeaurora.org> <20140116113332.GC25540@e102568-lin.cambridge.arm.com> <20140116180505.GA30925@codeaurora.org> <20140116183326.GG25540@e102568-lin.cambridge.arm.com> <20140116192617.GA13785@codeaurora.org> <20140117102109.GA22544@e102568-lin.cambridge.arm.com> <20140219002043.GE14769@codeaurora.org> <20140225111655.GA6855@e102568-lin.cambridge.arm.com> To: Lorenzo Pieralisi X-Mailer: Apple Mail (2.1827) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Feb 25, 2014, at 5:16 AM, Lorenzo Pieralisi wrote: > Hi Stephen, > > On Wed, Feb 19, 2014 at 12:20:43AM +0000, Stephen Boyd wrote: >> (Sorry, this discussion stalled due to merge window + life events) > > Sorry for the delay in replying on my side too. > >> On 01/17, Lorenzo Pieralisi wrote: >>> On Thu, Jan 16, 2014 at 07:26:17PM +0000, Stephen Boyd wrote: >>>> On 01/16, Lorenzo Pieralisi wrote: >>>>> On Thu, Jan 16, 2014 at 06:05:05PM +0000, Stephen Boyd wrote: >>>>>> On 01/16, Lorenzo Pieralisi wrote: >>>>>>> Do we really want to do that ? I am not sure. A cpus node is supposed to >>>>>>> be a container node, we should not define this binding just because we >>>>>>> know the kernel creates a platform device for it then. >>>>>> >>>>>> This is just copying more of the ePAPR spec into this document. >>>>>> It just so happens that having a compatible field here allows a >>>>>> platform device to be created. I don't see why that's a problem. >>>>> >>>>> I do not see why you cannot define a node like pmu or arch-timer and stick >>>>> a compatible property in there. cpus node does not represent a device, and >>>>> must not be created as a platform device, that's my opinion. >>>>> >>>> >>>> I had what you're suggesting before in the original revision of >>>> this patch. Please take a look at the original patch series[1]. I >>>> suppose it could be tweaked slightly to still have a cache node >>>> for the L2 interrupt and the next-level-cache pointer from the >>>> CPUs. >>> >>> Ok, sorry, we are running around in circles here, basically you moved >>> the node to cpus according to reviews. I still think that treating cpus >>> as a device is not a great idea, even though I am in the same >>> position with C-states and probably will add C-state tables in the cpus >>> node. >>> >>> http://comments.gmane.org/gmane.linux.power-management.general/41012 >>> >>> I just would like to see under cpus nodes and properties that apply to >>> all ARM systems, and avoid defining properties (eg interrupts) that >>> have different meanings for different ARM cores. >>> >>> The question related to why the kernel should create a platform device >>> out of cpus is still open. I really do not want to block your series >>> for these simple issues but we have to make a decision and stick to that, >>> I am fine either way if we have a plan. >>> >> >> Do you just want a backup plan in case we don't make a platform >> device out of the cpus node? I believe we can always add code >> somewhere to create a platform device at runtime if we detect the >> cpus node has a compatible string equal to "qcom,krait". We could >> probably change this driver's module_init() to scan the DT for >> such a compatible string and create the platform device right >> there. If we get more than one interrupt in the cpus node we can >> add interrupt-names and then have software look for interrupts by >> name instead of number. > > As I mentioned, I do not like the idea of adding compatible properties > just to force the kernel to create platform devices out of device tree > nodes. On top of that I would avoid adding a compatible property > to the cpus node (after all properties like enable-method are common for all > cpus but still duplicated), my only concern being backward compatibility > here (ie if we do that for interrupts, we should do that also for other > common cpu nodes properties, otherwise we have different rules for > different properties). > > I think you can then add interrupts to cpu nodes ("qcom,krait" specific), > and as you mentioned create a platform device for that. > > Thanks, > Lorenzo So I agree with the statement about adding compatibles just to create platform devices is wrong. However its seems perfectly reasonable for a cpu node to have a compatible property. I don?t see why a CPU is any different from any other device described in a DT. - k -- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/