From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7A63CC07E85 for ; Fri, 7 Dec 2018 13:45:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3FE7020868 for ; Fri, 7 Dec 2018 13:45:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3FE7020868 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726072AbeLGNpf (ORCPT ); Fri, 7 Dec 2018 08:45:35 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:44740 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726050AbeLGNpe (ORCPT ); Fri, 7 Dec 2018 08:45:34 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 33EAF15AB; Fri, 7 Dec 2018 05:45:34 -0800 (PST) Received: from e105550-lin.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A608C3F5AF; Fri, 7 Dec 2018 05:45:30 -0800 (PST) Date: Fri, 7 Dec 2018 13:45:21 +0000 From: Morten Rasmussen To: Atish Patra Cc: linux-kernel@vger.kernel.org, Albert Ou , Anup Patel , Ard Biesheuvel , Catalin Marinas , devicetree@vger.kernel.org, Dmitriy Cherkasov , Greg Kroah-Hartman , Ingo Molnar , Jeremy Linton , Juri Lelli , "moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)" , linux-riscv@lists.infradead.org, Mark Rutland , Palmer Dabbelt , "Peter Zijlstra (Intel)" , "Rafael J. Wysocki" , Rob Herring , Sudeep Holla , Thomas Gleixner , Will Deacon Subject: Re: [RFT PATCH v1 0/4] Unify CPU topology across ARM64 & RISC-V Message-ID: <20181207134509.GA5913@e105550-lin.cambridge.arm.com> References: <1543534100-3654-1-git-send-email-atish.patra@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1543534100-3654-1-git-send-email-atish.patra@wdc.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Thu, Nov 29, 2018 at 03:28:16PM -0800, Atish Patra wrote: > The cpu-map DT entry in ARM64 can describe the CPU topology in > much better way compared to other existing approaches. RISC-V can > easily adopt this binding to represent it's own CPU topology. > Thus, both cpu-map DT binding and topology parsing code can be > moved to a common location so that RISC-V or any other > architecture can leverage that. > > The relevant discussion regarding unifying cpu topology can be > found in [1]. > > arch_topology seems to be a perfect place to move the common > code. I have not introduced any functional changes in the moved > code. The only downside in this approach is that the capacity > code will be executed for RISC-V as well. But, it will exit > immediately after not able to find the appropriate DT node. If > the overhead is considered too much, we can always compile out > capacity related functions under a different config for the > architectures that do not support them. > > The patches have been tested for RISC-V and compile tested for > ARM64 & x86. The cpu-map bindings are used for arch/arm too, and so is arch_topology.c. In fact, it was introduced to allow code-sharing between arm and arm64. Applying patch three breaks arm. Moving the DT parsing to arch_topology.c we have to unify all three architectures. Be aware that arm and arm64 have some differences in how they detect cpu capacities. I think we might have to look at the split of code between arch/* and arch_topology.c again :-/ Morten