From patchwork Thu May 20 09:18:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 445607 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 F36C2C43461 for ; Thu, 20 May 2021 10:17:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D7E3160FE5 for ; Thu, 20 May 2021 10:17:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235248AbhETKTH (ORCPT ); Thu, 20 May 2021 06:19:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:47608 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235814AbhETKRR (ORCPT ); Thu, 20 May 2021 06:17:17 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A3BC36199D; Thu, 20 May 2021 09:46:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621503970; bh=Ijss7ILH0wpXAWgpiT4C5Kk8LSV4ypLf4ecaPXgNKCc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1gqGETfn7PSauqxmxexC3AsJ2nHM+MsQp6rOhBNtjFXriBlJCNnR4r6/Itq71Wcg4 z5eRmLXkOKwFxUpj7kQbRpkqM/yI+hwd0TCutLeadLhmjwi3o+/tAiBRw4n5BG6r89 VbBW+sjBQ+jzYyIWozm1SwMyN4UsyjAQohTraZaA= 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 4.14 036/323] PCI: PM: Do not read power state in pci_enable_device_flags() Date: Thu, 20 May 2021 11:18:48 +0200 Message-Id: <20210520092121.348625922@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210520092120.115153432@linuxfoundation.org> References: <20210520092120.115153432@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 c847b5554db6..1993e5e28ea7 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)