[lkml]   [2017]   [Dec]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH 4.14 89/95] drm/i915: Fix false-positive assert_rpm_wakelock_held in i915_pmic_bus_access_notifier v2
4.14-stable review patch.  If anyone has any objections, please let me know.


From: Hans de Goede <>

commit f4359cedfb43b934f38c50d1604db21333abe57b upstream.

assert_rpm_wakelock_held is triggered from i915_pmic_bus_access_notifier
even though it gets unregistered on (runtime) suspend, this is caused
by a race happening under the following circumstances:

intel_runtime_pm_put does:



And pm_runtime_put_autosuspend calls intel_runtime_suspend from
a workqueue, so there is ample of time between the atomic_dec() and
intel_runtime_suspend() unregistering the notifier. If the notifier
gets called in this windowd assert_rpm_wakelock_held falsely triggers
(at this point we're not runtime-suspended yet).

This commit adds disable_rpm_wakeref_asserts and
enable_rpm_wakeref_asserts calls around the
intel_uncore_forcewake_get(FORCEWAKE_ALL) call in
i915_pmic_bus_access_notifier fixing the false-positive WARN_ON.

Changes in v2:
-Reword comment explaining why disabling the wakeref asserts is
ok and necessary

Reported-by: FKr <>
Reviewed-by: Imre Deak <>
Signed-off-by: Hans de Goede <>
(cherry picked from commit ce30560c80dead91e98a03d90fb8791e57a9b69d)
Signed-off-by: Jani Nikula <>
Signed-off-by: Greg Kroah-Hartman <>

drivers/gpu/drm/i915/intel_uncore.c | 7 +++++++
1 file changed, 7 insertions(+)

--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1171,8 +1171,15 @@ static int i915_pmic_bus_access_notifier
* bus, which will be busy after this notification, leading to:
* "render: timed out waiting for forcewake ack request."
* errors.
+ *
+ * The notifier is unregistered during intel_runtime_suspend(),
+ * so it's ok to access the HW here without holding a RPM
+ * wake reference -> disable wakeref asserts for the time of
+ * the access.
+ disable_rpm_wakeref_asserts(dev_priv);
intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
+ enable_rpm_wakeref_asserts(dev_priv);
intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);

 \ /
  Last update: 2017-12-04 17:10    [W:0.250 / U:6.948 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site