[ 3.5.y.z extended stable ] Patch "PCI/PM: Fix fallback to PCI_D0 in" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    PCI/PM: Fix fallback to PCI_D0 in

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 05055f48472ef2178ed1e183720819d58b0099ff Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki at intel.com>
Date: Fri, 12 Apr 2013 13:58:17 +0000
Subject: [PATCH] PCI/PM: Fix fallback to PCI_D0 in
 pci_platform_power_transition()

commit 769ba7212f2059ca9fe0c73371e3d415c8c1c529 upstream.

Commit b51306c (PCI: Set device power state to PCI_D0 for device
without native PM support) modified pci_platform_power_transition()
by adding code causing dev->current_state for devices that don't
support native PCI PM but are power-manageable by the platform to be
changed to PCI_D0 regardless of the value returned by the preceding
platform_pci_set_power_state().  In particular, that also is done
if the platform_pci_set_power_state() has been successful, which
causes the correct power state of the device set by
pci_update_current_state() in that case to be overwritten by PCI_D0.

Fix that mistake by making the fallback to PCI_D0 only happen if
the platform_pci_set_power_state() has returned an error.

[bhelgaas: folded in Yinghai's simplification, added URL & stable info]
Reference: http://lkml.kernel.org/r/27806FC4E5928A408B78E88BBC67A2306F466BBA@ORSMSX101.amr.corp.intel.com
Reported-by: Chris J. Benenati <chris.j.benenati at intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
Acked-by: Yinghai Lu <yinghai at kernel.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/pci/pci.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 447e834..fa7c0f0 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -674,15 +674,11 @@ static int pci_platform_power_transition(struct pci_dev *dev, pci_power_t state)
 		error = platform_pci_set_power_state(dev, state);
 		if (!error)
 			pci_update_current_state(dev, state);
-		/* Fall back to PCI_D0 if native PM is not supported */
-		if (!dev->pm_cap)
-			dev->current_state = PCI_D0;
-	} else {
+	} else
 		error = -ENODEV;
-		/* Fall back to PCI_D0 if native PM is not supported */
-		if (!dev->pm_cap)
-			dev->current_state = PCI_D0;
-	}
+
+	if (error && !dev->pm_cap) /* Fall back to PCI_D0 */
+		dev->current_state = PCI_D0;

 	return error;
 }
--
1.8.1.2