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authorHans de Goede2017-11-10 16:03:01 +0100
committerJani Nikula2017-11-21 11:39:26 +0200
commitf4359cedfb43b934f38c50d1604db21333abe57b (patch)
treec3582ab4ed84577dfdd1f974ee2f9a596c462fdf /drivers/gpu/drm/i915
parente8c49fa96838101435b9e4884d49b30da7a4e0c6 (diff)
drm/i915: Fix false-positive assert_rpm_wakelock_held in i915_pmic_bus_access_notifier v2
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: atomic_dec(&dev_priv->pm.wakeref_count); pm_runtime_mark_last_busy(kdev); pm_runtime_put_autosuspend(kdev); 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 Cc: stable@vger.kernel.org Reported-by: FKr <bugs-freedesktop@ubermail.me> Reviewed-by: Imre Deak <imre.deak@intel.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20171110150301.9601-2-hdegoede@redhat.com (cherry picked from commit ce30560c80dead91e98a03d90fb8791e57a9b69d) Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Diffstat (limited to 'drivers/gpu/drm/i915')
-rw-r--r--drivers/gpu/drm/i915/intel_uncore.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 20e3c65c0999..cb48c8b92aa3 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1240,8 +1240,15 @@ static int i915_pmic_bus_access_notifier(struct notifier_block *nb,
* 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);
break;
case MBI_PMIC_BUS_ACCESS_END:
intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);