Re: [PATCH] PM / wakeirq: Fix dedicated wakeirq for drivers not using autosuspend

[Rafael J. Wysocki]

On Monday, December 05, 2016 04:38:16 PM Tony Lindgren wrote:
> 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 initially calls pm_runtime_get, 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.
> 
> Let's fix the issue by adding wirq->status that lazily gets set on
> the first rpm_suspend(). We also need PM runtime core private functions
> for dev_pm_enable_wake_irq_check() and dev_pm_disable_wake_irq_check()
> so we can enable the dedicated wakeirq on the first rpm_suspend().
> 
> While at it, let's also fix the comments for dev_pm_enable_wake_irq()
> and dev_pm_disable_wake_irq(). Those can still be used by the consumer
> drivers as needed because the irq core manages the interrupt usecount
> for us.
> 
> Fixes: 4990d4fe327b ("PM / Wakeirq: Add automated device wake IRQ
> handling")
> Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> ---
>  drivers/base/power/power.h   | 19 ++++++++++-
>  drivers/base/power/runtime.c |  8 ++---
>  drivers/base/power/wakeirq.c | 76 ++++++++++++++++++++++++++++++++++++++------
>  3 files changed, 88 insertions(+), 15 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
> @@ -21,14 +21,22 @@ extern void pm_runtime_init(struct device *dev);
>  extern void pm_runtime_reinit(struct device *dev);
>  extern void pm_runtime_remove(struct device *dev);
>  
> +#define WAKE_IRQ_DEDICATED_ALLOCATED	BIT(0)
> +#define WAKE_IRQ_DEDICATED_MANAGED	BIT(1)
> +#define WAKE_IRQ_DEDICATED_MASK		(WAKE_IRQ_DEDICATED_ALLOCATED | \
> +					 WAKE_IRQ_DEDICATED_MANAGED)
> +
>  struct wake_irq {
>  	struct device *dev;
> +	unsigned int status;
>  	int irq;
> -	bool dedicated_irq:1;
>  };
>  
>  extern void dev_pm_arm_wake_irq(struct wake_irq *wirq);
>  extern void dev_pm_disarm_wake_irq(struct wake_irq *wirq);
> +extern void dev_pm_enable_wake_irq_check(struct device *dev,
> +					 bool can_change_status);
> +extern void dev_pm_disable_wake_irq_check(struct device *dev);
>  
>  #ifdef CONFIG_PM_SLEEP
>  
> @@ -104,6 +112,15 @@ static inline void dev_pm_disarm_wake_irq(struct wake_irq *wirq)
>  {
>  }
>  
> +static inline void dev_pm_enable_wake_irq_check(struct device *dev,
> +						bool can_change_status)
> +{
> +}
> +
> +static inline void dev_pm_disable_wake_irq_check(struct device *dev)
> +{
> +}
> +
>  #endif
>  
>  #ifdef CONFIG_PM_SLEEP
> 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
> @@ -592,7 +592,7 @@ static int rpm_suspend(struct device *dev, int rpmflags)
>  
>  	callback = RPM_GET_CALLBACK(dev, runtime_suspend);
>  
> -	dev_pm_enable_wake_irq(dev);
> +	dev_pm_enable_wake_irq_check(dev, true);
>  	retval = rpm_callback(callback, dev);
>  	if (retval)
>  		goto fail;
> @@ -631,7 +631,7 @@ static int rpm_suspend(struct device *dev, int rpmflags)
>  	return retval;
>  
>   fail:
> -	dev_pm_disable_wake_irq(dev);
> +	dev_pm_disable_wake_irq_check(dev);
>  	__update_runtime_status(dev, RPM_ACTIVE);
>  	dev->power.deferred_resume = false;
>  	wake_up_all(&dev->power.wait_queue);
> @@ -814,12 +814,12 @@ static int rpm_resume(struct device *dev, int rpmflags)
>  
>  	callback = RPM_GET_CALLBACK(dev, runtime_resume);
>  
> -	dev_pm_disable_wake_irq(dev);
> +	dev_pm_disable_wake_irq_check(dev);
>  	retval = rpm_callback(callback, dev);
>  	if (retval) {
>  		__update_runtime_status(dev, RPM_SUSPENDED);
>  		pm_runtime_cancel_pending(dev);
> -		dev_pm_enable_wake_irq(dev);
> +		dev_pm_enable_wake_irq_check(dev, false);
>  	} else {
>   no_callback:
>  		__update_runtime_status(dev, RPM_ACTIVE);
> 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
> @@ -110,8 +110,10 @@ void dev_pm_clear_wake_irq(struct device *dev)
>  	dev->power.wakeirq = NULL;
>  	spin_unlock_irqrestore(&dev->power.lock, flags);
>  
> -	if (wirq->dedicated_irq)
> +	if (wirq->status & WAKE_IRQ_DEDICATED_ALLOCATED) {
>  		free_irq(wirq->irq, wirq);
> +		wirq->status &= ~WAKE_IRQ_DEDICATED_MASK;
> +	}
>  	kfree(wirq);
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_clear_wake_irq);
> @@ -181,7 +183,6 @@ int dev_pm_set_dedicated_wake_irq(struct device *dev, int irq)
>  
>  	wirq->dev = dev;
>  	wirq->irq = irq;
> -	wirq->dedicated_irq = true;
>  	irq_set_status_flags(irq, IRQ_NOAUTOEN);
>  
>  	/*
> @@ -197,6 +198,8 @@ int dev_pm_set_dedicated_wake_irq(struct device *dev, int irq)
>  	if (err)
>  		goto err_free_irq;
>  
> +	wirq->status = WAKE_IRQ_DEDICATED_ALLOCATED;
> +
>  	return err;
>  
>  err_free_irq:
> @@ -212,9 +215,9 @@ 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
> - * the device is running.
> + * Optionally called from the bus code or the device driver for
> + * runtime_resume() to override the PM runtime core managed wake-up
> + * interrupt handling to enable the wake-up interrupt.
>   *
>   * Note that for runtime_suspend()) the wake-up interrupts
>   * should be unconditionally enabled unlike for suspend()
> @@ -224,7 +227,7 @@ void dev_pm_enable_wake_irq(struct device *dev)
>  {
>  	struct wake_irq *wirq = dev->power.wakeirq;
>  
> -	if (wirq && wirq->dedicated_irq)
> +	if (wirq && (wirq->status & WAKE_IRQ_DEDICATED_ALLOCATED))
>  		enable_irq(wirq->irq);
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_enable_wake_irq);
> @@ -233,20 +236,73 @@ 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
> - * the device is running.
> + * Optionally called from the bus code or the device driver for
> + * runtime_suspend() to override the PM runtime core managed wake-up
> + * interrupt handling to disable the wake-up interrupt.
>   */
>  void dev_pm_disable_wake_irq(struct device *dev)
>  {
>  	struct wake_irq *wirq = dev->power.wakeirq;
>  
> -	if (wirq && wirq->dedicated_irq)
> +	if (wirq && (wirq->status & WAKE_IRQ_DEDICATED_ALLOCATED))
>  		disable_irq_nosync(wirq->irq);
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_disable_wake_irq);
>  
>  /**
> + * dev_pm_enable_wake_irq_check - Checks and enables wake-up interrupt
> + * @dev: Device
> + * @can_change_status: Can change wake-up interrupt status
> + *
> + * Enables wakeirq conditionally. We need to enable wake-up interrupt
> + * lazily on the first rpm_suspend(). This is needed as the consumer device
> + * starts in RPM_SUSPENDED state, and the the first pm_runtime_get() would
> + * otherwise try to disable already disabled wakeirq. The wake-up interrupt
> + * starts disabled with IRQ_NOAUTOEN set.
> + *
> + * Should be only called from rpm_suspend() and rpm_resume() path.
> + * Caller must hold &dev->power.lock to change wirq->status
> + */
> +void dev_pm_enable_wake_irq_check(struct device *dev,
> +				  bool can_change_status)
> +{
> +	struct wake_irq *wirq = dev->power.wakeirq;
> +
> +	if (!wirq || !((wirq->status & WAKE_IRQ_DEDICATED_MASK)))
> +		return;
> +
> +	if (likely(wirq->status & WAKE_IRQ_DEDICATED_MANAGED)) {
> +		goto enable;
> +	} else if (can_change_status) {
> +		wirq->status |= WAKE_IRQ_DEDICATED_MANAGED;
> +		goto enable;
> +	}
> +
> +	return;
> +
> +enable:
> +	enable_irq(wirq->irq);
> +}
> +
> +/**
> + * dev_pm_disable_wake_irq_check - Checks and disables wake-up interrupt
> + * @dev: Device
> + *
> + * Disables wake-up interrupt conditionally based on status.
> + * Should be only called from rpm_suspend() and rpm_resume() path.
> + */
> +void dev_pm_disable_wake_irq_check(struct device *dev)
> +{
> +	struct wake_irq *wirq = dev->power.wakeirq;
> +
> +	if (!wirq || !((wirq->status & WAKE_IRQ_DEDICATED_MASK)))
> +		return;
> +
> +	if (wirq->status & WAKE_IRQ_DEDICATED_MANAGED)
> +		disable_irq_nosync(wirq->irq);
> +}
> +
> +/**
>   * dev_pm_arm_wake_irq - Arm device wake-up
>   * @wirq: Device wake-up interrupt
>   *
> 

Applied.

Thanks,
Rafael