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authorImre Deak <imre.deak@intel.com>2016-04-18 14:45:54 +0300
committerJani Nikula <jani.nikula@intel.com>2016-04-27 10:37:54 +0300
commitdab9a2663f4e688106c041f7cd2797a721382f0a (patch)
tree3ea5dbea010be238f87fa351d7dade7ef3c909d4 /drivers
parent7ac7d19f808697abe6658c64c96868f728273f9c (diff)
drm/i915: Fix system resume if PCI device remained enabled
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. v2: - Add a code comment about the relation of this fix to the freeze/thaw vs. the suspend/resume phases. (Ville) - Add a code comment about the inconsistent ordering of set power state and device enable calls. (Chris) CC: Ville Syrjälä <ville.syrjala@linux.intel.com> CC: Chris Wilson <chris@chris-wilson.co.uk> CC: stable@vger.kernel.org Signed-off-by: Imre Deak <imre.deak@intel.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1460979954-14503-1-git-send-email-imre.deak@intel.com (cherry picked from commit 44410cd0bfb26bde9288da34c190cc9267d42a20) Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/gpu/drm/i915/i915_drv.c32
1 files changed, 31 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 30798cbc6fc0..6d2fb3f4ac62 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -792,7 +792,7 @@ 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
@@ -803,6 +803,36 @@ 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.
*/
+
+ /*
+ * 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);
+ goto out;
+ }
+
+ /*
+ * 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)) {
ret = -EIO;
goto out;