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=-12.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 172A5C433DF for ; Thu, 25 Jun 2020 11:31:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D4843207BB for ; Thu, 25 Jun 2020 11:31:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593084666; bh=QZi38O3Ut1h7YzJoaUyhp2CHCHV0usUcEWfCLDyFQ0A=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=RnkVskS0wqnowAqe4u149dIaRQysCbTxF5XIUQ0ANqA8BEAiRA8f1Va0pCHcnThhc os4H8XLBj/9TVhho2W055uxHAdL5JH4Vt9z+4IbtKYnaACXuvUoTELMD1ZLt8pEJNd +qtRkQXyKlXUevcfUD396kNI0N/hUkPYwhex/n54= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404226AbgFYLbG (ORCPT ); Thu, 25 Jun 2020 07:31:06 -0400 Received: from mail-oi1-f194.google.com ([209.85.167.194]:43031 "EHLO mail-oi1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404219AbgFYLbG (ORCPT ); Thu, 25 Jun 2020 07:31:06 -0400 Received: by mail-oi1-f194.google.com with SMTP id s10so4407243oih.10; Thu, 25 Jun 2020 04:31:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=ceR1V6p7RGNF++3XLjRXzuggrknx1RWLDfnDURTRa10=; b=kd3wbd1zjOuLTYKgkCuIDIVgLb5vg+vCuqGAtSBD6PZbdqrctAad5X/b4uidrtqUqA R4K9tFhcY/46nCrqCYoV2t2FI1aG0d/+vQSO2mx8eWy9OKQ/cisvng72tOQkI4Q5Q1l7 Qt5qsiaiJmfmunUH1akbwEhIQoPZB7+duOSKkqFIHODTGfnwGuD8Iu27xw4OsyxAsCYn kwW+kpPqGEx33zw8imLoEFMmKVF6j8lBr1AwskJQ+wJMKyw3bKNNXI2o7sE1HgTAdS0+ DkvYP4cHGp8PqtF4pNCRGEXnKnBWwqalGy0i5N6Px87/WQgtxsv7c9F3D8s/98m8Hz5P XqyQ== X-Gm-Message-State: AOAM532QD9YdNcMDv/dViOVwiQmT8mAecK8sh1UgJhTRz1TqJvqb+jgH Jx0GwpvlAtZhspBlZXs9FVMoLYr+1CoUBcx5n5E= X-Google-Smtp-Source: ABdhPJyklNBNQHH5j4xZ+MpbLP5vgIKFp9exs0rtM1iu2YH+8Aw6RTM6P9vtPnorNsBYobo61Jnpn1Fur6T/ALSpXvY= X-Received: by 2002:a54:4585:: with SMTP id z5mr1822683oib.110.1593084664345; Thu, 25 Jun 2020 04:31:04 -0700 (PDT) MIME-Version: 1.0 References: <20200612204820.20111-2-david.e.box@linux.intel.com> <20200624211549.GA2586552@bjorn-Precision-5520> In-Reply-To: <20200624211549.GA2586552@bjorn-Precision-5520> From: "Rafael J. Wysocki" Date: Thu, 25 Jun 2020 13:30:53 +0200 Message-ID: Subject: Re: [PATCH V2 1/2] PCI: Add ACPI StorageD3Enable _DSD support To: Bjorn Helgaas , Mika Westerberg Cc: "David E. Box" , shyjumon.n@intel.com, "Rafael J. Wysocki" , Len Brown , Bjorn Helgaas , Dan Williams , Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg , ACPI Devel Maling List , linux-nvme , Linux Kernel Mailing List , Linux PCI Content-Type: text/plain; charset="UTF-8" Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Wed, Jun 24, 2020 at 11:15 PM Bjorn Helgaas wrote: > > On Fri, Jun 12, 2020 at 01:48:19PM -0700, David E. Box wrote: > > StorageD3Enable is a boolean property that indicates that the platform > > wants to use D3 for PCIe storage drives during suspend-to-idle. It is a > > BIOS work around that is currently in use on shipping systems like some > > Intel Comet Lake platforms. It is meant to change default driver policy for > > suspend that may cause higher power consumption. > > > > Add the DSD property for recognition by fwnode calls and provide an > > exported symbol for device drivers to use to read the property as needed. > > > > Link: https://docs.microsoft.com/en-us/windows-hardware/design/component-guidelines/power-management-for-storage-hardware-devices-intro > > Signed-off-by: David E. Box > > --- > > drivers/acpi/property.c | 3 +++ > > drivers/pci/pci-acpi.c | 59 +++++++++++++++++++++++++++++++++++++++++ > > include/linux/pci.h | 2 ++ > > 3 files changed, 64 insertions(+) > > > > diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c > > index e601c4511a8b..c2e2ae774a19 100644 > > --- a/drivers/acpi/property.c > > +++ b/drivers/acpi/property.c > > @@ -45,6 +45,9 @@ static const guid_t prp_guids[] = { > > /* Thunderbolt GUID for WAKE_SUPPORTED: 6c501103-c189-4296-ba72-9bf5a26ebe5d */ > > GUID_INIT(0x6c501103, 0xc189, 0x4296, > > 0xba, 0x72, 0x9b, 0xf5, 0xa2, 0x6e, 0xbe, 0x5d), > > + /* Storage device needs D3 GUID: 5025030f-842f-4ab4-a561-99a5189762d0 */ > > + GUID_INIT(0x5025030f, 0x842f, 0x4ab4, > > + 0xa5, 0x61, 0x99, 0xa5, 0x18, 0x97, 0x62, 0xd0), > > }; > > > > /* ACPI _DSD data subnodes GUID: dbb8e3e6-5886-4ba6-8795-1319f52a966b */ > > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c > > index d21969fba6ab..732df524e09c 100644 > > --- a/drivers/pci/pci-acpi.c > > +++ b/drivers/pci/pci-acpi.c > > @@ -972,6 +972,65 @@ static bool acpi_pci_bridge_d3(struct pci_dev *dev) > > return val == 1; > > } > > > > +/** > > + * pci_acpi_storage_d3 - whether root port requests D3 for idle suspend > > + * @pdev: PCI device to check > > + * > > + * Returns true if the ACPI companion device contains the "StorageD3Enable" > > + * _DSD property and the value is 1. This indicates that the root port is > > + * used by a storage device and the platform is requesting D3 for the > > + * device during suspend to idle in order to support platform pm. > > + */ > > +bool pci_acpi_storage_d3(struct pci_dev *dev) > > +{ > > + const struct fwnode_handle *fwnode; > > + struct acpi_device *adev; > > + struct pci_dev *root; > > + acpi_handle handle; > > + acpi_status status; > > + bool ret = false; > > + u8 val; > > + > > + /* > > + * Look for _DSD property specifying that the storage device on > > + * the port must use D3 to support deep platform power savings during > > + * suspend-to-idle > > + */ > > + root = pci_find_pcie_root_port(dev); > > I think this would need to be updated to apply to v5.8-rc1 after > 6ae72bfa656e ("PCI: Unify pcie_find_root_port() and > pci_find_pcie_root_port()"). > > https://git.kernel.org/linus/6ae72bfa656e > > > + if (!root) > > + return false; > > + > > + adev = ACPI_COMPANION(&root->dev); > > + if (!adev) { > > + /* > > + * It is possible that the ACPI companion is not yet bound > > + * for the root port so look it up manually here. > > + */ > > + if (!adev && !pci_dev_is_added(root)) > > + adev = acpi_pci_find_companion(&root->dev); > > I see that you copied this "ACPI companion not yet bound" thing from > acpi_pci_bridge_d3(). But it's ugly. > > Isn't there a way we can bind the ACPI companion during normal PCI > enumeration so we don't need this exception case? > > I really do not like the idea of putting this code in the PCI core > because AFAICT the PCI core can do nothing with this information. > > If we could make sure during enumeration that the root port always has > an ACPI companion, this code could go to the nvme driver itself. And > we could also clean up the ugliness in acpi_pci_bridge_d3(). > > Rafael, is that possible? I don't really know how the companion > device gets set. That's a bit convoluted. device_add() calls device_platform_notify(), before calling bus_add_device(). device_platform_notify() calls acpi_platform_notify() which invokes acpi_device_notify() that looks for the companion via type->find_companion() which for PCI points to acpi_pci_find_companion(). If found, the companion is attached to the dev structure as a physical_node, via acpi_bind_one(). So by the time bus_probe_device() runs, the companion should be there already - if it is there at all. The parent ACPI companion should be present when the child is probing too, as per the above. > Maybe this is could be done somewhere around pci_device_add()? It is done in there. It is not necessary to call acpi_pci_find_companion() from pci_acpi_storage_d3() as long as that function is required to be called by the target device's driver probe or later. Ths acpi_pci_bridge_d3() case is different, though, AFAICS, because it is invoked in the pci_pm_init() path, via pci_bridge_d3_possible(), and that gets called from pci_device_add() *before* calling device_add(). Mika, is that why acpi_pci_find_companion() gets callled from acpi_pci_bridge_d3()?