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=-9.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 A561FC282C0 for ; Wed, 23 Jan 2019 16:56:42 +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 6D3C32085A for ; Wed, 23 Jan 2019 16:56:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="BfL61+Qa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6D3C32085A 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=u84y/YIU2qG4Z1fYJBQYqhniqsaso6BPUjfdf/b4dSM=; b=BfL61+QaAByt13 YoNrqQOois5Tb8riuZTgkXyIT33n8AFcZtyafewYNWvFfNEY9TXCu+NjBc4gm+aaMJa2BgMWAo2nu VqTvAKk4jyJyq49xu952NCekhSTuCCpUT+ENMWxQ7Zh9fNUvjXhB4P0cfnJ7cpj96mG4vbt0QLoBA dfPo+L26SGGCcCxddCEtN4B+tl8bDz4Toncr0wH0Io85rVp1Ph2aTy24vXs0FjRD+HWVzNYrs5D6B DfSxfOPG/G7sJOWRX9t+HdMT6QNJVvS5ar2ZH4d8YUJvsZSY8VckRDOLcSx3LrjhxViFY0VWHCurC i0K7yLRjeAlzCS7DiZng==; 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 1gmLpN-0001tR-0U; Wed, 23 Jan 2019 16:56:37 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gmLoy-0001YT-KU for linux-arm-kernel@lists.infradead.org; Wed, 23 Jan 2019 16:56:23 +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 EB282EBD; Wed, 23 Jan 2019 08:56:11 -0800 (PST) Received: from lakrids.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 D6CF03F237; Wed, 23 Jan 2019 08:56:09 -0800 (PST) Date: Wed, 23 Jan 2019 16:56:07 +0000 From: Mark Rutland To: Pramod Kumar Subject: Re: [PATCH RFC 1/1] arm64: Use PSCI calls for CPU stop when hotplug is supported Message-ID: <20190123165607.GB55887@lakrids.cambridge.arm.com> 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/1.11.1+11 (2f07cb52) (2018-12-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190123_085613_368981_C2154C96 X-CRM114-Status: GOOD ( 17.46 ) 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: 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. > > Apart from this, this gives control to f/w to reduce power consumption > by take appropriate decesion on power rails for plugging-out core. > > Signed-off-by: Pramod Kumar > Reviewed-by: Ray Jui > Reviewed-by: Scott Branden > --- > arch/arm64/kernel/smp.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index 1598d6f..360e52b 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -822,8 +822,13 @@ static void ipi_cpu_stop(unsigned int cpu) > local_daif_mask(); > sdei_mask_local_cpu(); > > +#ifdef CONFIG_HOTPLUG_CPU > + if (cpu_ops[cpu]->cpu_die) > + cpu_ops[cpu]->cpu_die(cpu); > +#else > while (1) > cpu_relax(); > +#endif If cpu_ops[cpu]->cpu_die is NULL, this change makes ipi_cpu_stop() return, which is not correct. Regardless, I don't think that there is sufficient rationale for this change, especially given that your commit message describes platform-specific assumptions which do not hold in general. Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel