releases/3.4.44/pci-pm-fix-fallback-to-pci_d0-in-pci_platform_power_transition.patch

   1 From 769ba7212f2059ca9fe0c73371e3d415c8c1c529 Mon Sep 17 00:00:00 2001
   2 From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
   3 Date: Fri, 12 Apr 2013 13:58:17 +0000
   4 Subject: PCI/PM: Fix fallback to PCI_D0 in pci_platform_power_transition()
   5
   6 From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
   7
   8 commit 769ba7212f2059ca9fe0c73371e3d415c8c1c529 upstream.
   9
  10 Commit b51306c (PCI: Set device power state to PCI_D0 for device
  11 without native PM support) modified pci_platform_power_transition()
  12 by adding code causing dev->current_state for devices that don't
  13 support native PCI PM but are power-manageable by the platform to be
  14 changed to PCI_D0 regardless of the value returned by the preceding
  15 platform_pci_set_power_state().  In particular, that also is done
  16 if the platform_pci_set_power_state() has been successful, which
  17 causes the correct power state of the device set by
  18 pci_update_current_state() in that case to be overwritten by PCI_D0.
  19
  20 Fix that mistake by making the fallback to PCI_D0 only happen if
  21 the platform_pci_set_power_state() has returned an error.
  22
  23 [bhelgaas: folded in Yinghai's simplification, added URL & stable info]
  24 Reference: http://lkml.kernel.org/r/27806FC4E5928A408B78E88BBC67A2306F466BBA@ORSMSX101.amr.corp.intel.com
  25 Reported-by: Chris J. Benenati <chris.j.benenati@intel.com>
  26 Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
  27 Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
  28 Acked-by: Yinghai Lu <yinghai@kernel.org>
  29 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  30
  31 ---
  32  drivers/pci/pci.c |   12 ++++--------
  33  1 file changed, 4 insertions(+), 8 deletions(-)
  34
  35 --- a/drivers/pci/pci.c
  36 +++ b/drivers/pci/pci.c
  37 @@ -673,15 +673,11 @@ static int pci_platform_power_transition
  38                 error = platform_pci_set_power_state(dev, state);
  39                 if (!error)
  40                         pci_update_current_state(dev, state);
  41 -               /* Fall back to PCI_D0 if native PM is not supported */
  42 -               if (!dev->pm_cap)
  43 -                       dev->current_state = PCI_D0;
  44 -       } else {
  45 +       } else
  46                 error = -ENODEV;
  47 -               /* Fall back to PCI_D0 if native PM is not supported */
  48 -               if (!dev->pm_cap)
  49 -                       dev->current_state = PCI_D0;
  50 -       }
  51 +
  52 +       if (error && !dev->pm_cap) /* Fall back to PCI_D0 */
  53 +               dev->current_state = PCI_D0;
  54
  55         return error;
  56  }