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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 831B6C433EF for ; Fri, 4 Feb 2022 07:10:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=TfCPficEdFefhXJm1eKbYAz0frOjIg8qKGJkgKRklr4=; b=oT5iWK/4Sbi/39QUc3KkZ/DKPe yRneq8C03rb9XqHwOpMktpUGi9kww77Bh11FGxEtBakU3PNJmxoWfEnUe8bMJAQO/2py5Yf3a3pWq mvTr7sE8B4pvE5LY5/FQKZGnT+fl5xz9KEPdMyRj6P12ik6YmSxaoiJkYu+TNkoRquTfzTf6gx41x 4JOFWPrfb3W1Mgj5kVPJKiLVp3OTFMMu5/w74mfNczTiRaYVG4LI6Iw49ZgmX2NLDha+o3/BVzTDn JmXlKSSeXQpcFebI6cvfFH5SnPB+UP14wXSs+vrntO+MkD6qfTd+9a8LpBeFZuazquABVf2vpA96A FVDI/YRw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nFsjb-003cVi-G7; Fri, 04 Feb 2022 07:10:19 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nFsjY-003cUz-KV for linux-nvme@lists.infradead.org; Fri, 04 Feb 2022 07:10:17 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 1407F68AFE; Fri, 4 Feb 2022 08:10:13 +0100 (CET) Date: Fri, 4 Feb 2022 08:10:12 +0100 From: Christoph Hellwig To: Keith Busch Cc: Christoph Hellwig , linux-nvme@lists.infradead.org, sagi@grimberg.me, Rafael Wysocki , Vidya Sagar Subject: Re: [PATCH] nvme/pci: default to simple suspend Message-ID: <20220204071012.GA28638@lst.de> References: <20220201165006.3074615-1-kbusch@kernel.org> <20220202075502.GA18474@lst.de> <20220202160334.GB3077632@dhcp-10-100-145-180.wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220202160334.GB3077632@dhcp-10-100-145-180.wdc.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220203_231016_850026_FC75BA93 X-CRM114-Status: GOOD ( 24.27 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Feb 02, 2022 at 08:03:34AM -0800, Keith Busch wrote: > On Wed, Feb 02, 2022 at 08:55:02AM +0100, Christoph Hellwig wrote: > > On Tue, Feb 01, 2022 at 08:50:06AM -0800, Keith Busch wrote: > > > There is no complete set of attributes a driver can check to know if > > > nvme power management is the correct thing to do in a runtime suspend > > > situation. Every attempt so far to optimize idle power consumption and > > > resume latency for a particular platform just leads to regressions > > > elsewhere. > > > > > > Default to the simple shutdown since it is the historically safest > > > option, and provide a user parameter to override it if the user knows > > > it's safe to use for their platform. > > > > Sigh. The platforms really should be asking for a explicit D3cold if > > they need one.. > > It's too late now, but perhaps the new property should have been > inverted since preparing for D3 was the previous default behavior; > platforms could have instead explicitly asked for "no-D3" if they wanted > it. That would have been easier for backward compatibility. I'd really prefer to sort this out at the platform level. We can't work around broken platforms in nvme forever.