This is a note to let you know that I've just added the patch titled
PM: runtime: Fix unpaired parent child_count for force_resume
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pm-runtime-fix-unpaired-parent-child_count-for-force_resume.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c745253e2a691a40c66790defe85c104a887e14a Mon Sep 17 00:00:00 2001
From: Tony Lindgren <tony@xxxxxxxxxxx>
Date: Wed, 5 May 2021 14:09:15 +0300
Subject: PM: runtime: Fix unpaired parent child_count for force_resume
From: Tony Lindgren <tony@xxxxxxxxxxx>
commit c745253e2a691a40c66790defe85c104a887e14a upstream.
As pm_runtime_need_not_resume() relies also on usage_count, it can return
a different value in pm_runtime_force_suspend() compared to when called in
pm_runtime_force_resume(). Different return values can happen if anything
calls PM runtime functions in between, and causes the parent child_count
to increase on every resume.
So far I've seen the issue only for omapdrm that does complicated things
with PM runtime calls during system suspend for legacy reasons:
omap_atomic_commit_tail() for omapdrm.0
dispc_runtime_get()
wakes up 58000000.dss as it's the dispc parent
dispc_runtime_resume()
rpm_resume() increases parent child_count
dispc_runtime_put() won't idle, PM runtime suspend blocked
pm_runtime_force_suspend() for 58000000.dss, !pm_runtime_need_not_resume()
__update_runtime_status()
system suspended
pm_runtime_force_resume() for 58000000.dss, pm_runtime_need_not_resume()
pm_runtime_enable() only called because of pm_runtime_need_not_resume()
omap_atomic_commit_tail() for omapdrm.0
dispc_runtime_get()
wakes up 58000000.dss as it's the dispc parent
dispc_runtime_resume()
rpm_resume() increases parent child_count
dispc_runtime_put() won't idle, PM runtime suspend blocked
...
rpm_suspend for 58000000.dss but parent child_count is now unbalanced
Let's fix the issue by adding a flag for needs_force_resume and use it in
pm_runtime_force_resume() instead of pm_runtime_need_not_resume().
Additionally omapdrm system suspend could be simplified later on to avoid
lots of unnecessary PM runtime calls and the complexity it adds. The
driver can just use internal functions that are shared between the PM
runtime and system suspend related functions.
Fixes: 4918e1f87c5f ("PM / runtime: Rework pm_runtime_force_suspend/resume()")
Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Tested-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Cc: 4.16+ <stable@xxxxxxxxxxxxxxx> # 4.16+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/base/power/runtime.c | 10 +++++++---
include/linux/pm.h | 1 +
2 files changed, 8 insertions(+), 3 deletions(-)
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1610,6 +1610,7 @@ void pm_runtime_init(struct device *dev)
dev->power.request_pending = false;
dev->power.request = RPM_REQ_NONE;
dev->power.deferred_resume = false;
+ dev->power.needs_force_resume = 0;
INIT_WORK(&dev->power.work, pm_runtime_work);
dev->power.timer_expires = 0;
@@ -1777,10 +1778,12 @@ int pm_runtime_force_suspend(struct devi
* its parent, but set its status to RPM_SUSPENDED anyway in case this
* function will be called again for it in the meantime.
*/
- if (pm_runtime_need_not_resume(dev))
+ if (pm_runtime_need_not_resume(dev)) {
pm_runtime_set_suspended(dev);
- else
+ } else {
__update_runtime_status(dev, RPM_SUSPENDED);
+ dev->power.needs_force_resume = 1;
+ }
return 0;
@@ -1807,7 +1810,7 @@ int pm_runtime_force_resume(struct devic
int (*callback)(struct device *);
int ret = 0;
- if (!pm_runtime_status_suspended(dev) || pm_runtime_need_not_resume(dev))
+ if (!pm_runtime_status_suspended(dev) || !dev->power.needs_force_resume)
goto out;
/*
@@ -1826,6 +1829,7 @@ int pm_runtime_force_resume(struct devic
pm_runtime_mark_last_busy(dev);
out:
+ dev->power.needs_force_resume = 0;
pm_runtime_enable(dev);
return ret;
}
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -608,6 +608,7 @@ struct dev_pm_info {
unsigned int idle_notification:1;
unsigned int request_pending:1;
unsigned int deferred_resume:1;
+ unsigned int needs_force_resume:1;
unsigned int runtime_auto:1;
bool ignore_children:1;
unsigned int no_callbacks:1;
Patches currently in stable-queue which might be from tony@xxxxxxxxxxx are
queue-5.4/pm-runtime-fix-unpaired-parent-child_count-for-force_resume.patch
