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=-3.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,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 9E230C43387 for ; Fri, 18 Jan 2019 11:33:02 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6DE35205C9 for ; Fri, 18 Jan 2019 11:33:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="pXqrmjzM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6DE35205C9 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-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=AyZyNBZT5nWlddANpyk9bmrzpS1b6zasHr1Mycqvy6c=; b=pXqrmjzMGCSNg2 SpfRoaudB4Nn+RgZ/Qb/6wubiu9y5DaYE58KmPgtKLdbILdRL2HEx5Y6FtFcR3XDD7AHfGjm+caGj g90nN88bGVTyteQP+bbjqLsb9t6iyCzvvIP5ynd5cFLJeA4dIEI2306b8/OaZUnpU338OKmcaWoKO 8UYQAxwbeakveVAG4tgxvuxnNFRpQ0xaH7kmjqerlD2brvQ9eDY5bof5/VZTmRUv8fsNgUFoJKTdm 7THjSGgjdczS1NzEfJAe0jtcq8CXX/N2uKQ4fhlExXne2ZMWBPvEFvouRYKZn9a6xwNhtVNNoDgd+ ujeMtcPgbanMjIgGDzGw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gkSOQ-0003cw-2g; Fri, 18 Jan 2019 11:32:58 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gkSOM-0003cM-N5 for linux-arm-kernel@lists.infradead.org; Fri, 18 Jan 2019 11:32:56 +0000 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 370D380D; Fri, 18 Jan 2019 03:32:53 -0800 (PST) Received: from e107155-lin (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F3AFE3F557; Fri, 18 Jan 2019 03:32:50 -0800 (PST) Date: Fri, 18 Jan 2019 11:32:42 +0000 From: Sudeep Holla To: Pramod Kumar Subject: Re: [PATCH RFC 1/1] arm64: Use PSCI calls for CPU stop when hotplug is supported Message-ID: <20190118113242.GA8928@e107155-lin> References: <1547790380-6276-1-git-send-email-pramod.kumar@broadcom.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1547790380-6276-1-git-send-email-pramod.kumar@broadcom.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190118_033254_755325_F96950BE X-CRM114-Status: GOOD ( 15.30 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Rob Herring , Lorenzo Pieralisi , Suzuki K Poulose , Catalin Marinas , Steve Capper , Will Deacon , linux-kernel@vger.kernel.org, BCM Kernel Feedback , Sudeep Holla , Dave Martin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jan 18, 2019 at 11:16:20AM +0530, Pramod Kumar wrote: > If CPU hotplug is supported, ipi_cpu_stop should use PSCI cpudie > call to stop the CPU. This call ensures L1/L2 cache flush, > CPUs cache-cohenrecy setting w.r.to interconnect. > Firstly, this is not specific to PSCI and I don't see any PSCI calls as $subject claims. Next, you fail to explain why do you have to ensure caches are cleaned and why do you need that in ipi_cpu_stop ? What's the use case ? > Apart from this, this gives control to f/w to reduce power consumption > by take appropriate decesion on power rails for plugging-out core. > May be, but ipi_cpu_stop is used is machine reboot/poweroff/halt which may restart or poweroff the system, powering down individual CPUs is not necessary and may consume lot of time in systems with large number of CPUs. It would be good to know the use-case in case I am missing to consider that. -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel