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    SubjectRe: platform/i2c busses: pm runtime and system sleep
    On Thu, Feb 17, 2011 at 20:55, Rabin Vincent <rabin@rab.in> wrote:
    > This will solve the platform vs AMBA bus, but shouldn't we really be
    > aiming for consistent behaviour between these and the other busses such
    > as I2C and SPI, which are also usually commonly used on the same
    > platforms and are using GENERIC_PM_OPS?
    >
    > Should we be auditing all platform drivers and then switch platform to
    > the GENERIC_PM_OPS?
    >
    > Or should the two points (1) and (2) be not handled in the bus at all
    > and be left to individual drivers (in which case we should audit i2c and
    > spi and change GENERIC_PM_OPS)?

    How about something like the below? If we have something like this, we
    can just switch platform to GENERIC_PM_OPS and add the
    pm_runtime_want_interaction() (or something better named) call to the
    i2c and spi drivers using runtime PM.

    diff --git a/drivers/base/power/generic_ops.c b/drivers/base/power/generic_ops.c
    index 42f97f9..c2a3b63 100644
    --- a/drivers/base/power/generic_ops.c
    +++ b/drivers/base/power/generic_ops.c
    @@ -87,7 +87,10 @@ static int __pm_generic_call(struct device *dev, int event)
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
    int (*callback)(struct device *);

    - if (!pm || pm_runtime_suspended(dev))
    + if (!pm)
    + return 0;
    +
    + if (device_want_interaction(dev) && pm_runtime_suspended(dev))
    return 0;

    switch (event) {
    @@ -185,7 +188,7 @@ static int __pm_generic_resume(struct device *dev,
    int event)
    return 0;

    ret = callback(dev);
    - if (!ret && pm_runtime_enabled(dev)) {
    + if (!ret && device_want_interaction(dev) && pm_runtime_enabled(dev)) {
    pm_runtime_disable(dev);
    pm_runtime_set_active(dev);
    pm_runtime_enable(dev);
    diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
    index 42615b4..2b8a099 100644
    --- a/drivers/base/power/runtime.c
    +++ b/drivers/base/power/runtime.c
    @@ -1069,6 +1069,30 @@ void pm_runtime_allow(struct device *dev)
    EXPORT_SYMBOL_GPL(pm_runtime_allow);

    /**
    + * pm_runtime_want_interaction - Enable interaction between system sleep
    + * and runtime PM callbacks at the bus/subsystem
    + * level.
    + * @dev: Device to handle
    + *
    + * Set the power.want_interaction flage, which tells the generic PM subsystem
    + * ops that the following actions should be done during system suspend/resume:
    + *
    + * - If the device has been runtime suspended, the driver's
    + * suspend() handler will not be invoked.
    + *
    + * - If the device has a resume() pm callback, and the resume()
    + * callback returns success on system resume, the device's
    + * runtime PM status will be set to active.
    + */
    +void pm_runtime_want_interaction(struct device *dev)
    +{
    + spin_lock_irq(&dev->power.lock);
    + dev->power.want_interaction = 1;
    + spin_unlock_irq(&dev->power.lock);
    +}
    +EXPORT_SYMBOL_GPL(pm_runtime_want_interaction);
    +
    +/**
    * pm_runtime_no_callbacks - Ignore run-time PM callbacks for a device.
    * @dev: Device to handle.
    *
    diff --git a/include/linux/pm.h b/include/linux/pm.h
    index dd9c7ab..b9bcfb9 100644
    --- a/include/linux/pm.h
    +++ b/include/linux/pm.h
    @@ -450,6 +450,7 @@ struct dev_pm_info {
    unsigned int irq_safe:1;
    unsigned int use_autosuspend:1;
    unsigned int timer_autosuspends:1;
    + unsigned int want_interaction:1;
    enum rpm_request request;
    enum rpm_status runtime_status;
    int runtime_error;
    diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
    index d34f067..a0e081b 100644
    --- a/include/linux/pm_runtime.h
    +++ b/include/linux/pm_runtime.h
    @@ -44,6 +44,7 @@ extern void pm_runtime_irq_safe(struct device *dev);
    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);
    +static void pm_runtime_want_system_sleep_interaction(struct device *dev);

    static inline bool pm_children_suspended(struct device *dev)
    {
    @@ -66,6 +67,11 @@ static inline void pm_runtime_put_noidle(struct device *dev)
    atomic_add_unless(&dev->power.usage_count, -1, 0);
    }

    +static inline bool device_want_interaction(struct device *dev)
    +{
    + return dev->power.want_interaction;
    +}
    +
    static inline bool device_run_wake(struct device *dev)
    {
    return dev->power.run_wake;
    @@ -122,6 +128,7 @@ static inline bool pm_children_suspended(struct
    device *dev) { return false; }
    static inline void pm_suspend_ignore_children(struct device *dev, bool en) {}
    static inline void pm_runtime_get_noresume(struct device *dev) {}
    static inline void pm_runtime_put_noidle(struct device *dev) {}
    +static inline bool device_want_interaction(struct device *dev) {
    return false; }
    static inline bool device_run_wake(struct device *dev) { return false; }
    static inline void device_set_run_wake(struct device *dev, bool enable) {}
    static inline bool pm_runtime_suspended(struct device *dev) { return false; }
    @@ -132,6 +139,7 @@ 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_irq_safe(struct device *dev) {}
    +static inline void pm_runtime_want_system_sleep_interaction(struct
    device *dev) {}

    static inline void pm_runtime_mark_last_busy(struct device *dev) {}
    static inline void __pm_runtime_use_autosuspend(struct device *dev,

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