[PATCH] PM / wakeirq: Fix wakeirq init

[Tony Lindgren]

I noticed some wakeirq flakeyness with consumer drivers not using
autosuspend. For drivers not using autosuspend, the wakeirq may never
get unmasked in rpm_suspend() because of irq desc->depth.

We are configuring dedicated wakeirqs to start with IRQ_NOAUTOEN as we
naturally don't want them running until rpm_suspend() is called.

However, when a consumer driver calls pm_runtime_get functions, we now
wrongly start with disable_irq_nosync() call on the dedicated wakeirq
that is disabled to start with.

This causes desc->depth to toggle between 1 and 2 instead of the usual
0 and 1. This can prevent enable_irq() from unmasking the wakeirq as
that only happens at desc->depth 1.

This does not necessarily show up with drivers using autosuspend as
there is time for disable_irq_nosync() before rpm_suspend() gets called
after the autosuspend timeout.

Fix the issue by adding wirq->active flag that lazily gets set on
the first rpm_suspend().

Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
---
 drivers/base/power/power.h   | 19 +++++++++++++++++++
 drivers/base/power/runtime.c |  1 +
 drivers/base/power/wakeirq.c | 10 ++++------
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -24,9 +24,24 @@ extern void pm_runtime_remove(struct device *dev);
 struct wake_irq {
 	struct device *dev;
 	int irq;
+	bool active:1;
 	bool dedicated_irq:1;
 };
 
+/* Caller must hold &dev->power.lock to change wirq->active */
+static inline void dev_pm_check_wake_irq(struct device *dev)
+{
+	struct wake_irq *wirq = dev->power.wakeirq;
+
+	if (!wirq)
+		return;
+
+	if (unlikely(!wirq->active)) {
+		wirq->active = true;
+		wmb();	/* ensure dev_pm_enable_wake_irq() sees active */
+	}
+}
+
 extern void dev_pm_arm_wake_irq(struct wake_irq *wirq);
 extern void dev_pm_disarm_wake_irq(struct wake_irq *wirq);
 
@@ -96,6 +111,10 @@ static inline void wakeup_sysfs_remove(struct device *dev) {}
 static inline int pm_qos_sysfs_add(struct device *dev) { return 0; }
 static inline void pm_qos_sysfs_remove(struct device *dev) {}
 
+static inline void dev_pm_check_wake_irq(struct device *dev)
+{
+}
+
 static inline void dev_pm_arm_wake_irq(struct wake_irq *wirq)
 {
 }
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -592,6 +592,7 @@ static int rpm_suspend(struct device *dev, int rpmflags)
 
 	callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 
+	dev_pm_check_wake_irq(dev);
 	dev_pm_enable_wake_irq(dev);
 	retval = rpm_callback(callback, dev);
 	if (retval)
diff --git a/drivers/base/power/wakeirq.c b/drivers/base/power/wakeirq.c
--- a/drivers/base/power/wakeirq.c
+++ b/drivers/base/power/wakeirq.c
@@ -212,8 +212,7 @@ EXPORT_SYMBOL_GPL(dev_pm_set_dedicated_wake_irq);
  * dev_pm_enable_wake_irq - Enable device wake-up interrupt
  * @dev: Device
  *
- * Called from the bus code or the device driver for
- * runtime_suspend() to enable the wake-up interrupt while
+ * Called from rpm_suspend() to enable the wake-up interrupt while
  * the device is running.
  *
  * Note that for runtime_suspend()) the wake-up interrupts
@@ -224,7 +223,7 @@ void dev_pm_enable_wake_irq(struct device *dev)
 {
 	struct wake_irq *wirq = dev->power.wakeirq;
 
-	if (wirq && wirq->dedicated_irq)
+	if (wirq && wirq->dedicated_irq && wirq->active)
 		enable_irq(wirq->irq);
 }
 EXPORT_SYMBOL_GPL(dev_pm_enable_wake_irq);
@@ -233,15 +232,14 @@ EXPORT_SYMBOL_GPL(dev_pm_enable_wake_irq);
  * dev_pm_disable_wake_irq - Disable device wake-up interrupt
  * @dev: Device
  *
- * Called from the bus code or the device driver for
- * runtime_resume() to disable the wake-up interrupt while
+ * Called from rpm_resume() to disable the wake-up interrupt while
  * the device is running.
  */
 void dev_pm_disable_wake_irq(struct device *dev)
 {
 	struct wake_irq *wirq = dev->power.wakeirq;
 
-	if (wirq && wirq->dedicated_irq)
+	if (wirq && wirq->dedicated_irq && wirq->active)
 		disable_irq_nosync(wirq->irq);
 }
 EXPORT_SYMBOL_GPL(dev_pm_disable_wake_irq);
-- 
2.10.2