From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sudeep Holla Subject: Re: [RFC 1/2] dt-bindings: topology: Add RISC-V cpu topology. Date: Fri, 2 Nov 2018 15:50:38 +0000 Message-ID: <20181102155038.GA21067@e107155-lin> References: <1541113468-22097-1-git-send-email-atish.patra@wdc.com> <1541113468-22097-2-git-send-email-atish.patra@wdc.com> <20181102133100.GA13130@e107155-lin> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Rob Herring Cc: Atish Patra , linux-riscv@lists.infradead.org, Palmer Dabbelt , Anup Patel , Christoph Hellwig , Damien.LeMoal@wdc.com, Thomas Gleixner , Mark Rutland , "linux-kernel@vger.kernel.org" , devicetree@vger.kernel.org, alankao@andestech.com, Sudeep Holla , Zong Li List-Id: devicetree@vger.kernel.org On Fri, Nov 02, 2018 at 10:11:38AM -0500, Rob Herring wrote: > On Fri, Nov 2, 2018 at 8:31 AM Sudeep Holla wrote: > > > > On Fri, Nov 02, 2018 at 08:09:39AM -0500, Rob Herring wrote: > > > On Thu, Nov 1, 2018 at 6:04 PM Atish Patra wrote: > > > > > > > > Define a RISC-V cpu topology. This is based on cpu-map in ARM world. > > > > But it doesn't need a separate thread node for defining SMT systems. > > > > Multiple cpu phandle properties can be parsed to identify the sibling > > > > hardware threads. Moreover, we do not have cluster concept in RISC-V. > > > > So package is a better word choice than cluster for RISC-V. > > > > > > There was a proposal to add package info for ARM recently. Not sure > > > what happened to that, but we don't need 2 different ways. > > > > > > > We still need that, I can brush it up and post what Lorenzo had previously > > proposed[1]. We want to keep both DT and ACPI CPU topology story aligned. > > Frankly, I don't care what the ACPI story is. I care whether each cpu Sorry I meant feature parity with ACPI and didn't refer to the mechanics. > arch does its own thing in DT or not. If a package prop works for > RISC-V folks and that happens to align with ACPI, then okay. Though I > tend to prefer a package represented as a node rather than a property > as I think that's more consistent. > Sounds good. One of the reason for making it *optional* property is for backward compatibility. But we should be able to deal with that even with node. > Any comments on the thread aspect (whether it has ever been used)? > Though I think thread as a node level is more consistent with each > topology level being a node (same with package). > Not 100% sure, the only multi threaded core in the market I know is Cavium TX2 which is ACPI. -- Regards, Sudeep