linux-kernel - [PATCH 3.2 050/140] PCI / PM: Force devices to D0 in pci_pm_thaw

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Message-ID: <lsq.1519831221.196894121@decadent.org.uk>
Date:   Wed, 28 Feb 2018 15:20:21 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Bjorn Helgaas" <bhelgaas@...gle.com>,
        "Maarten Lankhorst" <dev@...ankhorst.nl>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 3.2 050/140] PCI / PM: Force devices to D0 in
 pci_pm_thaw_noirq()

3.2.100-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>

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.

Fixes: e60514bd4485 (PCI/PM: Restore the status of PCI devices across hibernation)
Reported-by: Thomas Gleixner <tglx@...utronix.de>
Reported-by: Maarten Lankhorst <dev@...ankhorst.nl>
Tested-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Maarten Lankhorst <dev@...ankhorst.nl>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/pci/pci-driver.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -872,7 +872,12 @@ 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)