[PATCH 2/4] drm/i915: Fix system resume if PCI device remained enabled

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



During system resume we depended on pci_enable_device() also putting the
device into PCI D0 state. This won't work if the PCI device was already
enabled but still in D3 state. This is because pci_enable_device() is
refcounted and will not change the HW state if called with a non-zero
refcount. Leaving the device in D3 will make all subsequent device
accesses fail.

This didn't cause a problem most of the time, since we resumed with an
enable refcount of 0. But it fails at least after module reload because
after that we also happen to leak a PCI device enable reference: During
probing we call drm_get_pci_dev() which will enable the PCI device, but
during device removal drm_put_dev() won't disable it. This is a bug of
its own in DRM core, but without much harm as it only leaves the PCI
device enabled. Fixing it is also a bit more involved, due to DRM
mid-layering and because it affects non-i915 drivers too. The fix in
this patch is valid regardless of the problem in DRM core.

CC: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
---
 drivers/gpu/drm/i915/i915_drv.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index d550ae2..7eaa93e 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -803,7 +803,7 @@ static int i915_drm_resume(struct drm_device *dev)
 static int i915_drm_resume_early(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	int ret = 0;
+	int ret;
 
 	/*
 	 * We have a resume ordering issue with the snd-hda driver also
@@ -814,6 +814,13 @@ static int i915_drm_resume_early(struct drm_device *dev)
 	 * FIXME: This should be solved with a special hdmi sink device or
 	 * similar so that power domains can be employed.
 	 */
+
+	ret = pci_set_power_state(dev->pdev, PCI_D0);
+	if (ret) {
+		DRM_ERROR("failed to set PCI D0 power state (%d)\n", ret);
+		goto out;
+	}
+
 	if (pci_enable_device(dev->pdev)) {
 		ret = -EIO;
 		goto out;
-- 
2.5.0

--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]