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=-2.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 03C12C04EB5 for ; Fri, 7 Feb 2020 16:05:38 +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 C81DD21775 for ; Fri, 7 Feb 2020 16:05:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="htooYq5S" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C81DD21775 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=gFSLz0uIroRyj42tyysC3BlmObZjW/9Gcu0nyHeVn70=; b=htooYq5SxOXJxQ 9nVSN0/xmaX/iYDJsimiQw9pZIiOSBm5K/lX0SthJANO+6hVm+WFiPTkGGclKwVBg3qL14+nw47bZ NmJISH77qbrbPy0crMItB2dIK6qVoIXGb+KawkKxd3LECPHq5+0815vHQO2MChIoV93JHHDcArm+5 RJRGzXZGw33+E/G5sAxB/BvRfuuZPyZ67IYVqSrWzLfAfXLxGB5NGAl+EpSjaxw853fp15YANq5DR Prkl1hOJLk5S89E+4HtnhYXemxX9Yray/9x1o5xiIprsykgHpYbCWZrKLy7O9NVTOi9Bjyl8sRLj6 GzaaCDa5K4qLyMxZmoAQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j068G-0007gf-UE; Fri, 07 Feb 2020 16:05:28 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j068D-0007g7-JJ for linux-arm-kernel@lists.infradead.org; Fri, 07 Feb 2020 16:05:27 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id EDECE1FB; Fri, 7 Feb 2020 08:05:24 -0800 (PST) Received: from bogus (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BD1DA3F68E; Fri, 7 Feb 2020 08:05:22 -0800 (PST) Date: Fri, 7 Feb 2020 16:05:13 +0000 From: Sudeep Holla To: Ulf Hansson Subject: Re: [PATCH v3 5/7] drivers: firmware: psci: Add hierarchical domain idle states converter Message-ID: <20200207160504.GA8342@bogus> References: <0d7f7ade-3a1e-5428-d851-f1a886f58712@codeaurora.org> <20200204152132.GA44858@bogus> <6ff7c82d-4204-a339-4070-0154ab4515f1@codeaurora.org> <20200205140603.GB38466@bogus> <20200205161816.GD38466@bogus> <20200206204514.GB8107@codeaurora.org> <20200207111955.GA40103@bogus> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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-20200207_080525_724492_0EB77110 X-CRM114-Status: GOOD ( 20.48 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Maulik Shah , lsrao@codeaurora.org, Lorenzo Pieralisi , Rajendra Nayak , Linux PM , linux-arm-msm , "Rafael J. Wysocki" , Linux Kernel Mailing List , Lina Iyer , Stephen Boyd , David Brown , Andy Gross , Evan Green , Doug Anderson , Sudeep Holla , Bjorn Andersson , Linux ARM 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, Feb 07, 2020 at 01:32:28PM +0100, Ulf Hansson wrote: > [...] > > > > I understand the arguments for using PC vs OSI and agree with it. But > > > what in PSCI is against Linux knowing when the last core is powering > > > down when the PSCI is configured to do only Platform Cordinated. > > > > Nothing :D. But knowing the evolution and reasons for adding OSI in the > > PSCI specification and having argued about benefits of OSI over PC for > > years and finally when we have it in mainline, this argument of using > > PC for exact reasons why OSI evolved is something I can't understand > > and I am confused. > > > > > There should not be any objection to drivers knowing when all the cores > > > are powered down, be it reference counting CPU PM notifications or using > > > a cleaner approach like this where GendPD framwork does everything > > > cleanly and gives a nice callback. ARM architecture allows for different > > > aspects of CPU access be handled at different levels. I see this as an > > > extension of that approach. > > > > > > > One thing that was repeatedly pointed out during OSI patch review was no > > extra overhead for PC mode where firmware can make decisions. So, just > > use OSI now and let us be done with this discussion of OSI vs PC. If PC > > is what you think you need for future, we can revert all OSI changes and > > start discussing again :-) > > Just to make it clear, I fully agree with you in regards to overhead > for PC-mode. This is especially critical for ARM SoCs with lots of > cores, I assume. > > However, the overhead you refer to, is *only* going to be present in > case when the DTS has the hierarchical CPU topology description with > "power-domains". Because, that is *optional* to use, I am expecting > only those SoC/platforms that needs to manage last-man activities to > use this layout, the others will remain unaffected. > > That said, does that address your concern? > I have already expressed my view and concerns in response to Lina and Bjorn's emails. -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel