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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 6367CC433FF for ; Thu, 8 Aug 2019 20:03:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 25A2C2184E for ; Thu, 8 Aug 2019 20:03:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565294636; bh=XKTewYNW5u4u5EpWVDYYrn/auYfBYt+Fs75L4VKojK0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=rmcc+hV+kV+iUc/fE8AGBS8Q30mp/nQZXWSX0ZKXDWnOiB4z2qgQYY4bvmRJjYvV5 KsButstdGOWeVcAZFGmEYG75Xjrkz/C02/h+I2NKTvtyzj66v+QTfRM5DKD4aseSlY zES5tf2Xxck3a3sJUd9bLyrTwi434Ews8ZfwP4qw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390211AbfHHUDz (ORCPT ); Thu, 8 Aug 2019 16:03:55 -0400 Received: from mga11.intel.com ([192.55.52.93]:35369 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389883AbfHHUDz (ORCPT ); Thu, 8 Aug 2019 16:03:55 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Aug 2019 13:03:54 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,362,1559545200"; d="scan'208";a="165801725" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by orsmga007.jf.intel.com with ESMTP; 08 Aug 2019 13:03:53 -0700 Date: Thu, 8 Aug 2019 14:01:28 -0600 From: Keith Busch To: Bjorn Helgaas Cc: "Rafael J. Wysocki" , "Rafael J. Wysocki" , linux-nvme , Mario Limonciello , Kai-Heng Feng , Keith Busch , Christoph Hellwig , Sagi Grimberg , Linux PM , Linux Kernel Mailing List , Rajat Jain , Linux PCI Subject: Re: [PATCH v2 2/2] nvme-pci: Allow PCI bus-level PM to be used if ASPM is disabled Message-ID: <20190808200128.GC27077@localhost.localdomain> References: <4323ed84dd07474eab65699b4d007aaf@AUSX13MPC105.AMER.DELL.COM> <20190731221956.GB15795@localhost.localdomain> <1921165.pTveHRX1Co@kreacher> <1870928.r7tBYyfqdz@kreacher> <20190808134356.GF151852@google.com> <20190808183954.GG151852@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190808183954.GG151852@google.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, Aug 08, 2019 at 01:39:54PM -0500, Bjorn Helgaas wrote: > On Thu, Aug 08, 2019 at 04:47:45PM +0200, Rafael J. Wysocki wrote: > > On Thu, Aug 8, 2019 at 3:43 PM Bjorn Helgaas wrote: > > > > > IIUC the NVMe device will go to the desired package idle state if > > > the link is in L0s or L1, but not if the link is in L0. I don't > > > understand that connection; AFAIK that would be something outside > > > the scope of the PCIe spec. > > > > Yes, it is outside of the PCIe spec. > > > > No, this is not about the NVMe device, it is about the Intel SoC > > (System-on-a-Chip) the platform is based on. > > Ah. So this problem could occur with any device, not just NVMe? If > so, how do you address that? Obviously you don't want to patch all > drivers this way. We discovered this when using an NVMe protocol specific power setting, so that part is driver specific. We just have to ensure device generic dependencies are met in order to achieve the our power target. So in that sense, I think you would need to patch all drivers if they're also using protocol specific settings incorrectly. Granted, the NVMe specification doesn't detail what PCIe settings may prevent NVMe power management from hitting the objective, but I think ASPM enabled makes sense.