From patchwork Thu May 20 09:20:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 444184 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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 563C5C43461 for ; Thu, 20 May 2021 10:46:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3BFB360FDC for ; Thu, 20 May 2021 10:46:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238358AbhETKr2 (ORCPT ); Thu, 20 May 2021 06:47:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:44686 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235988AbhETKp2 (ORCPT ); Thu, 20 May 2021 06:45:28 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BCBA361C9E; Thu, 20 May 2021 09:57:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621504655; bh=epoxyg1iQQQqX4jq1V0SOFBd2DwpkwT06OGtZXs0IHE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AoW4Iw+3/BzyQmmpga7sOOo5rE7cuc76ZPDgUKz5wxX/dy1JVpHDm2OC4+vJEJ1XU IDa2a7vp90tdsWeuaraV1cmAqFp5dGF1vej+CIxXXAgttiWd8jdWYXEvlKjS7njW/R VKelIQoDJQ7hL1YxN5haTwKrNJ2WenCwyzzDnSMM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Maximilian Luz , "Rafael J. Wysocki" , Mika Westerberg , Sasha Levin Subject: [PATCH 4.9 020/240] PCI: PM: Do not read power state in pci_enable_device_flags() Date: Thu, 20 May 2021 11:20:12 +0200 Message-Id: <20210520092109.301595504@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210520092108.587553970@linuxfoundation.org> References: <20210520092108.587553970@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Rafael J. Wysocki [ Upstream commit 4514d991d99211f225d83b7e640285f29f0755d0 ] It should not be necessary to update the current_state field of struct pci_dev in pci_enable_device_flags() before calling do_pci_enable_device() for the device, because none of the code between that point and the pci_set_power_state() call in do_pci_enable_device() invoked later depends on it. Moreover, doing that is actively harmful in some cases. For example, if the given PCI device depends on an ACPI power resource whose _STA method initially returns 0 ("off"), but the config space of the PCI device is accessible and the power state retrieved from the PCI_PM_CTRL register is D0, the current_state field in the struct pci_dev representing that device will get out of sync with the power.state of its ACPI companion object and that will lead to power management issues going forward. To avoid such issues it is better to leave the current_state value as is until it is changed to PCI_D0 by do_pci_enable_device() as appropriate. However, the power state of the device is not changed to PCI_D0 if it is already enabled when pci_enable_device_flags() gets called for it, so update its current_state in that case, but use pci_update_current_state() covering platform PM too for that. Link: https://lore.kernel.org/lkml/20210314000439.3138941-1-luzmaximilian@gmail.com/ Reported-by: Maximilian Luz Tested-by: Maximilian Luz Signed-off-by: Rafael J. Wysocki Reviewed-by: Mika Westerberg Signed-off-by: Sasha Levin --- drivers/pci/pci.c | 16 +++------------- 1 file changed, 3 insertions(+), 13 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index e09653c73ab4..acd89fa9820c 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1378,20 +1378,10 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags) int err; int i, bars = 0; - /* - * Power state could be unknown at this point, either due to a fresh - * boot or a device removal call. So get the current power state - * so that things like MSI message writing will behave as expected - * (e.g. if the device really is in D0 at enable time). - */ - if (dev->pm_cap) { - u16 pmcsr; - pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr); - dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK); - } - - if (atomic_inc_return(&dev->enable_cnt) > 1) + if (atomic_inc_return(&dev->enable_cnt) > 1) { + pci_update_current_state(dev, dev->current_state); return 0; /* already enabled */ + } bridge = pci_upstream_bridge(dev); if (bridge)