[ 039/136 ] PCI/PM: Fix fallback to PCI_D0 in pci_platform_power_transition()

From: Steven Rostedt
Date: Fri May 17 2013 - 22:21:39 EST stable review patch.
If anyone has any objections, please let me know.


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

[ Upstream commit 769ba7212f2059ca9fe0c73371e3d415c8c1c529 ]

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@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: Chris J. Benenati <chris.j.benenati@xxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Acked-by: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v3.2+
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
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 a0f8e8f..466b669 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -663,15 +663,11 @@ 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;

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