This is a note to let you know that I've just added the patch titled
drm/i915: Fix false-positive assert_rpm_wakelock_held in i915_pmic_bus_access_notifier v2
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: drm-i915-fix-false-positive-assert_rpm_wakelock_held-in-i915_pmic_bus_access_notifier-v2.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From f4359cedfb43b934f38c50d1604db21333abe57b Mon Sep 17 00:00:00 2001
From: Hans de Goede j.w.r.degoede@gmail.com Date: Fri, 10 Nov 2017 16:03:01 +0100 Subject: drm/i915: Fix false-positive assert_rpm_wakelock_held in i915_pmic_bus_access_notifier v2
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);
Patches currently in stable-queue which might be from j.w.r.degoede@gmail.com are
queue-4.14/drm-i915-re-register-pmic-bus-access-notifier-on-runtime-resume.patch queue-4.14/drm-i915-fix-false-positive-assert_rpm_wakelock_held-in-i915_pmic_bus_access_notifier-v2.patch