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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49F5DC433EF for ; Fri, 4 Feb 2022 23:32:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238967AbiBDXcY (ORCPT ); Fri, 4 Feb 2022 18:32:24 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:36458 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234948AbiBDXcY (ORCPT ); Fri, 4 Feb 2022 18:32:24 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 20D2DB83972; Fri, 4 Feb 2022 23:32:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46B27C340ED; Fri, 4 Feb 2022 23:32:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644017542; bh=GR4dOo1Lfdor0ypIQE86E4qvS3wJM1AIXoiFnVPF5CE=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=kd2LxVPMtefRU+J6mZuTfmxv1ztG9Zjqq3Jdt/WMKDQn1pyoksiDaauoevWiQ9oaY Z0kt3n+FQsWwURS6zDAhAl1HL2j7HfE5I1GRdmzjxW2VmfpRiojzRgc6xWEnxv9oj3 +H0sBZRXIBN+S8csXLa4k7k5V7dzX2SzycdVL1IYJPzAVSk22ecB2D4OBkeXpyMQQV Yb1qHozcXAPysFIfA1JsVcgx5rTvvSkNQNBQWdNNqbnnPf5BWDCMotW5Mgj2Ktmd/J G6qzzYNFFVFkKyyQz8nNFHQs/BdwfnFPScTBCm/4GsvGb6HK+9KK7jGpDc3rxW2KjQ 9zgM1bkfwn4kA== Date: Fri, 4 Feb 2022 17:32:19 -0600 From: Bjorn Helgaas To: Abhishek Sahu Cc: Bjorn Helgaas , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, "Rafael J. Wysocki" Subject: Re: [PATCH] PCI: Fix the ACPI power state during runtime resume Message-ID: <20220204233219.GA228585@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220124122107.12148-1-abhsahu@nvidia.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org [+cc Rafael, hoping for your review :) Wonder if we should add something like this to MAINTAINERS so you get cc'd on power-related things: diff --git a/MAINTAINERS b/MAINTAINERS index ea3e6c914384..3d9a211cad5d 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -15422,6 +15422,7 @@ F: include/linux/pm.h F: include/linux/pm_* F: include/linux/powercap.h F: kernel/configs/nopm.config +K: pci_[a-z_]*power[a-z_]*\( DYNAMIC THERMAL POWER MANAGEMENT (DTPM) M: Daniel Lezcano ] On Mon, Jan 24, 2022 at 05:51:07PM +0530, Abhishek Sahu wrote: > Consider the following sequence during PCI device runtime > suspend/resume: > > 1. PCI device goes into runtime suspended state. The PCI state > will be changed to PCI_D0 and then pci_platform_power_transition() > will be called which changes the ACPI state to ACPI_STATE_D3_HOT. > > 2. Parent bridge goes into runtime suspended state. If parent > bridge supports D3cold, then it will change the power state of all its > children to D3cold state and the power will be removed. > > 3. During wake-up time, the bridge will be runtime resumed first > and pci_power_up() will be called for the bridge. Now, the power > supply will be resumed. > > 4. pci_resume_bus() will be called which will internally invoke > pci_restore_standard_config(). pci_update_current_state() > will read PCI_PM_CTRL register and the current_state will be > updated to D0. > > In the above process, at step 4, the ACPI device state will still be > ACPI_STATE_D3_HOT since pci_platform_power_transition() is not being > invoked. We need call the pci_platform_power_transition() with state > D0 to change the ACPI state to ACPI_STATE_D0. > > This patch calls pci_power_up() if current power state is D0 inside > pci_restore_standard_config(). This pci_power_up() will change the > ACPI state to ACPI_STATE_D0. > > Following are the steps to confirm: > > Enable the debug prints in acpi_pci_set_power_state() > > 0000:01:00.0 is PCI device and 0000:00:01.0 is parent bridge device > > Before: > > 0000:01:00.0: power state changed by ACPI to D3hot > 0000:00:01.0: power state changed by ACPI to D3cold > 0000:00:01.0: power state changed by ACPI to D0 > > After: > > 0000:01:00.0: power state changed by ACPI to D3hot > 0000:00:01.0: power state changed by ACPI to D3cold > 0000:00:01.0: power state changed by ACPI to D0 > 0000:01:00.0: power state changed by ACPI to D0 > > So with this patch, the PCI device ACPI state is also being > changed to D0. > > Signed-off-by: Abhishek Sahu > --- > drivers/pci/pci-driver.c | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c > index 588588cfda48..64e0cca12f16 100644 > --- a/drivers/pci/pci-driver.c > +++ b/drivers/pci/pci-driver.c > @@ -521,14 +521,22 @@ static void pci_device_shutdown(struct device *dev) > */ > static int pci_restore_standard_config(struct pci_dev *pci_dev) > { > + int error = 0; > pci_update_current_state(pci_dev, PCI_UNKNOWN); > > if (pci_dev->current_state != PCI_D0) { > - int error = pci_set_power_state(pci_dev, PCI_D0); > - if (error) > - return error; > + error = pci_set_power_state(pci_dev, PCI_D0); > + } else { > + /* > + * The platform power state can still be non-D0, so this is > + * required to change the platform power state to D0. > + */ > + error = pci_power_up(pci_dev); > } > > + if (error) > + return error; > + > pci_restore_state(pci_dev); > pci_pme_restore(pci_dev); > return 0; > -- > 2.17.1 >