Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756610AbdLOO2P (ORCPT ); Fri, 15 Dec 2017 09:28:15 -0500 Received: from mail-oi0-f68.google.com ([209.85.218.68]:41411 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755739AbdLOO2M (ORCPT ); Fri, 15 Dec 2017 09:28:12 -0500 X-Google-Smtp-Source: ACJfBovWVaKfYG0ouqQsuNCeHZK4EOY6WckohjtFbfPzPD5K1k38IxUDRKuN49Q3IMQn6Ear1081kd6O5Yin7LKnXnk= MIME-Version: 1.0 In-Reply-To: <2582328.YfNXS1jHhG@aspire.rjw.lan> References: <168050887.sZlTFXWCmO@aspire.rjw.lan> <11146834.AWaDHrVcmB@aspire.rjw.lan> <2582328.YfNXS1jHhG@aspire.rjw.lan> From: "Rafael J. Wysocki" Date: Fri, 15 Dec 2017 15:28:11 +0100 X-Google-Sender-Auth: 8llMeXpMw2468QnINpKh-NEMCLs Message-ID: Subject: Re: [PATCH] PCI / PM: Force devices to D0 in pci_pm_thaw_noirq() To: Bjorn Helgaas Cc: Thomas Gleixner , Linux PCI , Linus Torvalds , Maarten Lankhorst , Michal Hocko , Andy Lutomirski , Linux Kernel Mailing List , "the arch/x86 maintainers" , Daniel Vetter , Bjorn Helgaas , "Rafael J. Wysocki" , Linux PM , Chen Yu Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2249 Lines: 52 On Fri, Dec 15, 2017 at 3:07 AM, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > It is incorrect to call pci_restore_state() for devices in low-power > states (D1-D3), as that involves the restoration of MSI setup which > requires MMIO to be operational and that is only the case in D0. > > However, pci_pm_thaw_noirq() may do that if the driver's "freeze" > callbacks put the device into a low-power state, so fix it by making > it force devices into D0 via pci_set_power_state() instead of trying > to "update" their power state which is pointless. > > Fixes: e60514bd4485 (PCI/PM: Restore the status of PCI devices across hibernation) > Cc: 4.13+ # 4.13+ > Reported-by: Thomas Gleixner > Reported-by: Maarten Lankhorst > Tested-by: Thomas Gleixner > Tested-by: Maarten Lankhorst > Signed-off-by: Rafael J. Wysocki > --- > > The bug is not as old as I thought, actually. > > Yes, we did the pci_update_current_state() in pci_pm_thaw_noirq() > forever, but it started to be problematic in 4.13, when we started > to call pci_restore_state() in addition to it to fix another issue. Bjorn, any concerns about this one? > --- > drivers/pci/pci-driver.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > Index: linux-pm/drivers/pci/pci-driver.c > =================================================================== > --- linux-pm.orig/drivers/pci/pci-driver.c > +++ linux-pm/drivers/pci/pci-driver.c > @@ -1027,7 +1027,12 @@ static int pci_pm_thaw_noirq(struct devi > if (pci_has_legacy_pm_support(pci_dev)) > return pci_legacy_resume_early(dev); > > - pci_update_current_state(pci_dev, PCI_D0); > + /* > + * pci_restore_state() requires the device to be in D0 (because of MSI > + * restoration among other things), so force it into D0 in case the > + * driver's "freeze" callbacks put it into a low-power state directly. > + */ > + pci_set_power_state(pci_dev, PCI_D0); > pci_restore_state(pci_dev); > > if (drv && drv->pm && drv->pm->thaw_noirq) >