Hi,
On Thursday, September 30, 2010, Alan Stern wrote:
> This patch (as1431) adds a synchronous runtime-PM interface suitable
> for use in interrupt handlers. Four new helper functions are defined:
>
> pm_runtime_suspend_irq(), pm_runtime_resume_irq(),
> pm_runtime_get_sync_irq(), pm_runtime_put_sync_irq(),
>
> together with pm_runtime_callbacks_in_irq(), which subsystems use to
> tell the PM core that the runtime callbacks should be invoked with
> interrupts disabled.
>
> Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
>
> ---
>
> In the end it turned out that a new RPM_IRQ call flag was needed along
> with the callbacks_in_irq flag in dev_pm_info. The latter is required
> for the reasons I explained before, and RPM_IRQ tells the core whether
> or not it must leave interrupts disabled while waiting for a concurrent
> state change.
>
> Kevin, this should be good enough to satisfy all your needs. How does
> it look?
>
> Alan Stern
>
>
> Index: usb-2.6/include/linux/pm.h
> ===================================================================
> --- usb-2.6.orig/include/linux/pm.h
> +++ usb-2.6/include/linux/pm.h
> @@ -485,6 +485,7 @@ struct dev_pm_info {
> unsigned int run_wake:1;
> unsigned int runtime_auto:1;
> unsigned int no_callbacks:1;
> + unsigned int callbacks_in_irq:1;
I kind of don't like this name. What about irq_safe ?
> unsigned int use_autosuspend:1;
> unsigned int timer_autosuspends:1;
> enum rpm_request request;
> Index: usb-2.6/include/linux/pm_runtime.h
> ===================================================================
> --- usb-2.6.orig/include/linux/pm_runtime.h
> +++ usb-2.6/include/linux/pm_runtime.h
> @@ -21,6 +21,7 @@
> #define RPM_GET_PUT 0x04 /* Increment/decrement the
> usage_count */
> #define RPM_AUTO 0x08 /* Use autosuspend_delay */
> +#define RPM_IRQ 0x10 /* Don't enable interrupts */
>
> #ifdef CONFIG_PM_RUNTIME
>
> @@ -40,6 +41,7 @@ extern int pm_generic_runtime_idle(struc
> extern int pm_generic_runtime_suspend(struct device *dev);
> extern int pm_generic_runtime_resume(struct device *dev);
> extern void pm_runtime_no_callbacks(struct device *dev);
> +extern void pm_runtime_callbacks_in_irq(struct device *dev);
Perhaps this one can be called pm_runtime_irq_safe() in analogy to the struct
member?
> extern void __pm_runtime_use_autosuspend(struct device *dev, bool use);
> extern void pm_runtime_set_autosuspend_delay(struct device *dev, int delay);
> extern unsigned long pm_runtime_autosuspend_expiration(struct device *dev);
> @@ -123,6 +125,7 @@ static inline int pm_generic_runtime_idl
> static inline int pm_generic_runtime_suspend(struct device *dev) { return 0; }
> static inline int pm_generic_runtime_resume(struct device *dev) { return 0; }
> static inline void pm_runtime_no_callbacks(struct device *dev) {}
> +static inline void pm_runtime_callbacks_in_irq(struct device *dev) {}
>
> static inline void pm_runtime_mark_last_busy(struct device *dev) {}
> static inline void __pm_runtime_use_autosuspend(struct device *dev,
> @@ -144,6 +147,11 @@ static inline int pm_runtime_suspend(str
> return __pm_runtime_suspend(dev, 0);
> }
>
> +static inline int pm_runtime_suspend_irq(struct device *dev)
> +{
> + return __pm_runtime_suspend(dev, RPM_IRQ);
> +}
> +
> static inline int pm_runtime_autosuspend(struct device *dev)
> {
> return __pm_runtime_suspend(dev, RPM_AUTO);
> @@ -154,6 +162,11 @@ static inline int pm_runtime_resume(stru
> return __pm_runtime_resume(dev, 0);
> }
>
> +static inline int pm_runtime_resume_irq(struct device *dev)
> +{
> + return __pm_runtime_resume(dev, RPM_IRQ);
> +}
> +
> static inline int pm_request_idle(struct device *dev)
> {
> return __pm_runtime_idle(dev, RPM_ASYNC);
> @@ -179,6 +192,11 @@ static inline int pm_runtime_get_sync(st
> return __pm_runtime_resume(dev, RPM_GET_PUT);
> }
>
> +static inline int pm_runtime_get_sync_irq(struct device *dev)
> +{
> + return __pm_runtime_resume(dev, RPM_GET_PUT | RPM_IRQ);
> +}
> +
> static inline int pm_runtime_put(struct device *dev)
> {
> return __pm_runtime_idle(dev, RPM_GET_PUT | RPM_ASYNC);
> @@ -195,6 +213,11 @@ static inline int pm_runtime_put_sync(st
> return __pm_runtime_idle(dev, RPM_GET_PUT);
> }
>
> +static inline int pm_runtime_put_sync_irq(struct device *dev)
> +{
> + return __pm_runtime_idle(dev, RPM_GET_PUT | RPM_IRQ);
> +}
> +
> static inline int pm_runtime_put_sync_autosuspend(struct device *dev)
> {
> return __pm_runtime_suspend(dev, RPM_GET_PUT | RPM_AUTO);
> Index: usb-2.6/drivers/base/power/runtime.c
> ===================================================================
> --- usb-2.6.orig/drivers/base/power/runtime.c
> +++ usb-2.6/drivers/base/power/runtime.c
> @@ -170,10 +170,13 @@ static int rpm_idle(struct device *dev,
> __releases(&dev->power.lock) __acquires(&dev->power.lock)
> {
> int retval;
> + int (*func)(struct device *dev);
>
> retval = rpm_check_suspend_allowed(dev);
> if (retval < 0)
> ; /* Conditions are wrong. */
> + else if ((rpmflags & RPM_IRQ) && !dev->power.callbacks_in_irq)
> + retval = -EWOULDBLOCK;
>
> /* Idle notifications are allowed only in the RPM_ACTIVE state. */
> else if (dev->power.runtime_status != RPM_ACTIVE)
> @@ -214,25 +217,27 @@ static int rpm_idle(struct device *dev,
>
> dev->power.idle_notification = true;
>
> - if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_idle) {
> - spin_unlock_irq(&dev->power.lock);
> -
> - dev->bus->pm->runtime_idle(dev);
> -
> - spin_lock_irq(&dev->power.lock);
> - } else if (dev->type && dev->type->pm && dev->type->pm->runtime_idle) {
> - spin_unlock_irq(&dev->power.lock);
> + func = NULL;
> + if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_idle)
> + func = dev->bus->pm->runtime_idle;
> + else if (dev->type && dev->type->pm && dev->type->pm->runtime_idle)
> + func = dev->type->pm->runtime_idle;
> + else if (dev->class && dev->class->pm && dev->class->pm->runtime_idle)
> + func = dev->class->pm->runtime_idle;
> + if (func) {
> + if (dev->power.callbacks_in_irq) {
> + spin_unlock(&dev->power.lock);
Hmm. This looks rather complicated. I don't really feel good about this
change. It seems to me that it might be better to actually implement
the _irq() helpers from scratch. I think I'll try to do that.
Overall, it looks like there's some overlap between RPM_IRQ and
power.callbacks_in_irq, where the latter may influence the behavior of the
helpers even if RPM_IRQ is unset.
I think we should return error code if RPM_IRQ is used, but
power.callbacks_in_irq is not set. If RPM_IRQ is not set, but
power.callbacks_in_irq is set, we should fall back to the normal behavior
(ie. do not avoid sleeping).
That's why I think it's better to change the name of power.callbacks_in_irq
to power.irq_safe.
Also I think we should refuse to set power.callbacks_in_irq for a device
whose partent (1) doesn't have power.callbacks_in_irq and (2) doesn't
have power.ignore_children set , and (3) doesn't have power.disable_depth > 0.
Then, once we've set power.callbacks_in_irq for a device, we should take
this into consideration when trying to change the parent's settings.
There probably is more subtelties like this, but I can't see them at the moment.
Thanks,
Rafael
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