drm/i915: Fix system resume if PCI device remained enabled

[pandora-kernel.git] / drivers / gpu / drm / i915 / i915_drv.c

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 452bc51..e216c21 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -538,6 +538,35 @@ int i915_resume(struct drm_device *dev)
        if (dev->switch_power_state == DRM_SWITCH_POWER_OFF)
                return 0;
 
+       /*
+        * Note that we need to set the power state explicitly, since we
+        * powered off the device during freeze and the PCI core won't power
+        * it back up for us during thaw. Powering off the device during
+        * freeze is not a hard requirement though, and during the
+        * suspend/resume phases the PCI core makes sure we get here with the
+        * device powered on. So in case we change our freeze logic and keep
+        * the device powered we can also remove the following set power state
+        * call.
+        */
+       ret = pci_set_power_state(dev->pdev, PCI_D0);
+       if (ret) {
+               DRM_ERROR("failed to set PCI D0 power state (%d)\n", ret);
+               return ret;
+       }
+
+       /*
+        * Note that pci_enable_device() first enables any parent bridge
+        * device and only then sets the power state for this device. The
+        * bridge enabling is a nop though, since bridge devices are resumed
+        * first. The order of enabling power and enabling the device is
+        * imposed by the PCI core as described above, so here we preserve the
+        * same order for the freeze/thaw phases.
+        *
+        * TODO: eventually we should remove pci_disable_device() /
+        * pci_enable_enable_device() from suspend/resume. Due to how they
+        * depend on the device enable refcount we can't anyway depend on them
+        * disabling/enabling the device.
+        */
        if (pci_enable_device(dev->pdev))
                return -EIO;