From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: [PATCH] PCI / PM: Force devices to D0 in pci_pm_thaw_noirq() Date: Fri, 15 Dec 2017 03:07:18 +0100 Message-ID: <2582328.YfNXS1jHhG@aspire.rjw.lan> References: <168050887.sZlTFXWCmO@aspire.rjw.lan> <11146834.AWaDHrVcmB@aspire.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <11146834.AWaDHrVcmB@aspire.rjw.lan> Sender: linux-pci-owner@vger.kernel.org To: Thomas Gleixner , linux-pci@vger.kernel.org Cc: Linus Torvalds , Bjorn Helgaas , Maarten Lankhorst , Michal Hocko , Andy Lutomirski , Linux Kernel Mailing List , the arch/x86 maintainers , Daniel Vetter , Bjorn Helgaas , "Rafael J. Wysocki" , linux-pm@vger.kernel.org, Chen Yu List-Id: linux-pm@vger.kernel.org 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. --- 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)