Patch "PCI / PM: Force devices to D0 in pci_pm_thaw_noirq()" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

PCI / PM: Force devices to D0 in pci_pm_thaw_noirq()

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
pci-pm-force-devices-to-d0-in-pci_pm_thaw_noirq.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Rafael J. Wysocki" <[email protected]>
Date: Fri, 15 Dec 2017 03:07:18 +0100
Subject: PCI / PM: Force devices to D0 in pci_pm_thaw_noirq()

From: Rafael J. Wysocki <[email protected]>

commit 5839ee7389e893a31e4e3c9cf17b50d14103c902 upstream.

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.

---
 drivers/pci/pci-driver.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

@@ -968,7 +968,12 @@ 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)

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/pci-pm-force-devices-to-d0-in-pci_pm_thaw_noirq.patch queue-4.14/acpi-apei-erst-fix-missing-error-handling-in-erst_reader.patch