On Thursday, November 01, 2012 06:47:26 PM Lan Tianyu wrote:
> If pm qos flags was changed, device driver would take different
> action according flags. E.g NO_POWER_OFF flag, if it was set when
> a device had been power off, device driver should power on the device,
> resume it and suspend it again without not power off. So device driver
> should be notified. This patch is to add notifier for pm qos flags and
> notify device when flags is changed.
>
> Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
I haven't added notifiers for PM QoS flags on purpose, so I'm not going
to apply this patch.
Instead, it is required that callers of dev_pm_qos_update_request() for
DEV_PM_QOS_FLAGS type of requests ensure that the device is not RPM_SUSPENDED
when calling that routine (please note that the user interface calls
pm_runtime_get_sync() on the device before changing its flags). Well, I think
I should add that to the kerneldoc comment of dev_pm_qos_update_request().
Moreover, I'm planning to remove the notifiers from the device PM QoS code
entirely and change the locking so that dev_pm_qos_update_request() and
friends may be called from interrupt context (which is necessary for some
use cases).
Thanks,
Rafael
> ---
> drivers/base/power/qos.c | 86 +++++++++++++++++++++++++++++++++++++---------
> include/linux/pm_qos.h | 7 ++--
> 2 files changed, 75 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
> index 31d3f48..c37f52f 100644
> --- a/drivers/base/power/qos.c
> +++ b/drivers/base/power/qos.c
> @@ -149,6 +149,10 @@ static int apply_constraint(struct dev_pm_qos_request *req,
> case DEV_PM_QOS_FLAGS:
> ret = pm_qos_update_flags(&qos->flags, &req->data.flr,
> action, value);
> + if (ret)
> + blocking_notifier_call_chain(qos->flags.notifiers,
> + (unsigned long)qos->flags.effective_flags,
> + req);
> break;
> default:
> ret = -EINVAL;
> @@ -168,26 +172,38 @@ static int dev_pm_qos_constraints_allocate(struct device *dev)
> {
> struct dev_pm_qos *qos;
> struct pm_qos_constraints *c;
> - struct blocking_notifier_head *n;
> + struct pm_qos_flags *flags;
> + struct blocking_notifier_head *constraints_notify;
> + struct blocking_notifier_head *flags_notify;
> + int ret = 0;
>
> qos = kzalloc(sizeof(*qos), GFP_KERNEL);
> if (!qos)
> return -ENOMEM;
>
> - n = kzalloc(sizeof(*n), GFP_KERNEL);
> - if (!n) {
> - kfree(qos);
> - return -ENOMEM;
> + constraints_notify = kzalloc(sizeof(*constraints_notify), GFP_KERNEL);
> + if (!constraints_notify) {
> + ret = -ENOMEM;
> + goto alloc_constraints_fail;
> + }
> + BLOCKING_INIT_NOTIFIER_HEAD(constraints_notify);
> +
> + flags_notify = kzalloc(sizeof(*flags_notify), GFP_KERNEL);
> + if (!flags_notify) {
> + ret = -ENOMEM;
> + goto alloc_flags_fail;
> }
> - BLOCKING_INIT_NOTIFIER_HEAD(n);
> + BLOCKING_INIT_NOTIFIER_HEAD(flags_notify);
>
> c = &qos->latency;
> plist_head_init(&c->list);
> c->target_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
> c->default_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
> c->type = PM_QOS_MIN;
> - c->notifiers = n;
> + c->notifiers = constraints_notify;
>
> + flags = &qos->flags;
> + flags->notifiers = flags_notify;
> INIT_LIST_HEAD(&qos->flags.list);
>
> spin_lock_irq(&dev->power.lock);
> @@ -195,6 +211,12 @@ static int dev_pm_qos_constraints_allocate(struct device *dev)
> spin_unlock_irq(&dev->power.lock);
>
> return 0;
> +
> +alloc_flags_fail:
> + kfree(constraints_notify);
> +alloc_constraints_fail:
> + kfree(qos);
> + return ret;
> }
>
> /**
> @@ -432,6 +454,7 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
> *
> * @dev: target device for the constraint
> * @notifier: notifier block managed by caller.
> + * @type: type of notifier
> *
> * Will register the notifier into a notification chain that gets called
> * upon changes to the target value for the device.
> @@ -439,9 +462,11 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
> * If the device's constraints object doesn't exist when this routine is called,
> * it will be created (or error code will be returned if that fails).
> */
> -int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
> +int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier,
> + enum dev_pm_qos_req_type type)
> {
> int ret = 0;
> + struct blocking_notifier_head *notifiers_head = NULL;
>
> mutex_lock(&dev_pm_qos_mtx);
>
> @@ -449,9 +474,22 @@ int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
> ret = dev->power.power_state.event != PM_EVENT_INVALID ?
> dev_pm_qos_constraints_allocate(dev) : -ENODEV;
>
> - if (!ret)
> - ret = blocking_notifier_chain_register(
> - dev->power.qos->latency.notifiers, notifier);
> + if (!ret) {
> + switch (type) {
> + case DEV_PM_QOS_LATENCY:
> + notifiers_head = dev->power.qos->latency.notifiers;
> + break;
> + case DEV_PM_QOS_FLAGS:
> + notifiers_head = dev->power.qos->flags.notifiers;
> + break;
> + default:
> + break;
> + }
> +
> + if (notifiers_head)
> + ret = blocking_notifier_chain_register(
> + notifiers_head, notifier);
> + }
>
> mutex_unlock(&dev_pm_qos_mtx);
> return ret;
> @@ -464,22 +502,38 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);
> *
> * @dev: target device for the constraint
> * @notifier: notifier block to be removed.
> + * @type: type of notifier
> *
> * Will remove the notifier from the notification chain that gets called
> * upon changes to the target value.
> */
> int dev_pm_qos_remove_notifier(struct device *dev,
> - struct notifier_block *notifier)
> + struct notifier_block *notifier, enum dev_pm_qos_req_type type)
> {
> int retval = 0;
> + struct blocking_notifier_head *notifiers_head = NULL;
> +
>
> mutex_lock(&dev_pm_qos_mtx);
>
> /* Silently return if the constraints object is not present. */
> - if (dev->power.qos)
> - retval = blocking_notifier_chain_unregister(
> - dev->power.qos->latency.notifiers,
> - notifier);
> + if (dev->power.qos) {
> + switch (type) {
> + case DEV_PM_QOS_LATENCY:
> + notifiers_head = dev->power.qos->latency.notifiers;
> + break;
> + case DEV_PM_QOS_FLAGS:
> + notifiers_head = dev->power.qos->flags.notifiers;
> + break;
> + default:
> + break;
> + }
> +
> + if (notifiers_head)
> + retval = blocking_notifier_chain_unregister(
> + notifiers_head,
> + notifier);
> + }
>
> mutex_unlock(&dev_pm_qos_mtx);
> return retval;
> diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
> index 5a95013..479da6c 100644
> --- a/include/linux/pm_qos.h
> +++ b/include/linux/pm_qos.h
> @@ -84,6 +84,7 @@ struct pm_qos_constraints {
> struct pm_qos_flags {
> struct list_head list;
> s32 effective_flags; /* Do not change to 64 bit */
> + struct blocking_notifier_head *notifiers;
> };
>
> struct dev_pm_qos {
> @@ -134,9 +135,11 @@ int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
> int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value);
> int dev_pm_qos_remove_request(struct dev_pm_qos_request *req);
> int dev_pm_qos_add_notifier(struct device *dev,
> - struct notifier_block *notifier);
> + struct notifier_block *notifier,
> + enum dev_pm_qos_req_type type);
> int dev_pm_qos_remove_notifier(struct device *dev,
> - struct notifier_block *notifier);
> + struct notifier_block *notifier,
> + enum dev_pm_qos_req_type type);
> int dev_pm_qos_add_global_notifier(struct notifier_block *notifier);
> int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier);
> void dev_pm_qos_constraints_init(struct device *dev);
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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