4.14-stable review patch. If anyone has any objections, please let me know.
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From: Hans de Goede j.w.r.degoede@gmail.com
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:
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
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... (cherry picked from commit ce30560c80dead91e98a03d90fb8791e57a9b69d) Signed-off-by: Jani Nikula jani.nikula@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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); break; case MBI_PMIC_BUS_ACCESS_END: intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);