Received: by 2002:a25:4158:0:0:0:0:0 with SMTP id o85csp2155961yba; Fri, 10 May 2019 07:08:55 -0700 (PDT) X-Google-Smtp-Source: APXvYqwfx9P6vDnf9ZRKXxW7w/dqMSl4GM0t8DfumoV8pBuWOodzDG97/4gMY4LPCxD7MBlbkhxO X-Received: by 2002:aa7:93ba:: with SMTP id x26mr14255240pff.238.1557497335192; Fri, 10 May 2019 07:08:55 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1557497335; cv=none; d=google.com; s=arc-20160816; b=zNx8I7OX5L77TMUJ6rZTnW0mq6/7isVLl4+ezLX5Uar268Pp4RG4pFFZKTsBbpWP+X ZMX0AoKcbPCn0Q1nYY8CUDigz/QE/Q4HIMD1Ugm2WObye9IxpL+VDwfSbAdFnjsvlw0g z2gNQalT41kwKS7LFBPUliTr+YE7iXrh5+xgsOyeaxPxR92cOHlEwK8WSDFXPOg3kgtm 6AWa90TPuVvU83fC2XWrBiXN43vfCmR+9fSNjU4EpMp/SrAFO+TPZNaA1fbz3oWLq7rv iMpZ0XQfH1Zj0J+zXsNfTDwceOH+ygQEhGp9whGpd6K6zsofFgymW9ipUID5L9bokcI/ cUog== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:user-agent:in-reply-to :content-transfer-encoding:content-disposition:mime-version :references:message-id:subject:cc:to:from:date; bh=TTrUBidn6UU8DxjMxi/Fm9iX1fq4DaHVVWe/zLWW4qA=; b=b/gmZ0OAO+oU/fRH0S+Gjv4/HgTR3LKt0JQ8uMRtOGb6LbqXjMaSGQi7CY3iPt3/SS wGsdx3ksg5J/xZX80wKbgqiQgJwc8FOOo7GDjd23I5aQiKbeB7DVaKmJIIpAEjFxmSJZ 4RytwYrx6Y1BhCz6q5bFGNk3ivzJztc2RQJ2STAEA6uB94e/v2Bm1G9bsZpKxB8hfn6S 0oXEnLVrlteKYJlGoV8Blv9TReS51tCbS0USvyBeOW7TdXB3SaZZ7MlID0ATfp9dmiQA XKofwhmtS9Xj+792x1y4djTY7Wdysp63GALUqgIVjejZrArjedj6akczpFGRvpUgqGBz I0Ug== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id r140si7070379pgr.585.2019.05.10.07.08.36; Fri, 10 May 2019 07:08:55 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727767AbfEJOHj (ORCPT + 99 others); Fri, 10 May 2019 10:07:39 -0400 Received: from mga03.intel.com ([134.134.136.65]:32011 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727572AbfEJOHi (ORCPT ); Fri, 10 May 2019 10:07:38 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 May 2019 07:07:38 -0700 X-ExtLoop1: 1 Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by orsmga007.jf.intel.com with ESMTP; 10 May 2019 07:07:37 -0700 Date: Fri, 10 May 2019 08:02:09 -0600 From: Keith Busch To: Kai-Heng Feng Cc: "Mario.Limonciello@dell.com" , "hch@lst.de" , "axboe@fb.com" , "sagi@grimberg.me" , "rafael@kernel.org" , "linux-pm@vger.kernel.org" , "Wysocki, Rafael J" , "linux-kernel@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "Busch, Keith" Subject: Re: [PATCH] nvme-pci: Use non-operational power state instead of D3 on Suspend-to-Idle Message-ID: <20190510140209.GG9675@localhost.localdomain> References: <20190509095601.GA19041@lst.de> <225CF4F7-C8E1-4C66-B362-97E84596A54E@canonical.com> <20190509103142.GA19550@lst.de> <31b7d7959bf94c15a04bab0ced518444@AUSX13MPC101.AMER.DELL.COM> <20190509192807.GB9675@localhost.localdomain> <7a002851c435481593f8629ec9193e40@AUSX13MPC101.AMER.DELL.COM> <20190509215409.GD9675@localhost.localdomain> <495d76c66aec41a8bfbbf527820f8eb9@AUSX13MPC101.AMER.DELL.COM> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 09, 2019 at 11:05:42PM -0700, Kai-Heng Feng wrote: > Yes, that’ what I was told by the NVMe vendor, so all I know is to impose a > memory barrier. > If mb() shouldn’t be used here, what’s the correct variant to use in this > context? I'm afraid the requirement is still not clear to me. AFAIK, all our barriers routines ensure data is visible either between CPUs, or between CPU and devices. The CPU never accesses HMB memory, so there must be some other reasoning if this barrier is a real requirement for this device.