Commit 3a4a0042 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

PM: QoS: Drop PM_QOS_CPU_DMA_LATENCY notifier chain 



Notice that pm_qos_remove_notifier() is not used at all and the only
caller of pm_qos_add_notifier() is the cpuidle core, which only needs
the PM_QOS_CPU_DMA_LATENCY notifier to invoke wake_up_all_idle_cpus()
upon changes of the PM_QOS_CPU_DMA_LATENCY target value.

First, to ensure that wake_up_all_idle_cpus() will be called
whenever the PM_QOS_CPU_DMA_LATENCY target value changes, modify the
pm_qos_add/update/remove_request() family of functions to check if
the effective constraint for the PM_QOS_CPU_DMA_LATENCY has changed
and call wake_up_all_idle_cpus() directly in that case.

Next, drop the PM_QOS_CPU_DMA_LATENCY notifier from cpuidle as it is
not necessary any more.

Finally, drop both pm_qos_add_notifier() and pm_qos_remove_notifier(),
as they have no callers now, along with cpu_dma_lat_notifier which is
only used by them.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Reviewed-by: default avatarAmit Kucheria <amit.kucheria@linaro.org>
Tested-by: default avatarAmit Kucheria <amit.kucheria@linaro.org>
parent 02c92a37

drivers/cpuidle/cpuidle.c

+1 −39
Original line number Diff line number Diff line
@@ -736,53 +736,15 @@ int cpuidle_register(struct cpuidle_driver *drv, 
}

EXPORT_SYMBOL_GPL(cpuidle_register);



#ifdef CONFIG_SMP



/*

 * This function gets called when a part of the kernel has a new latency

 * requirement.  This means we need to get all processors out of their C-state,

 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that

 * wakes them all right up.

 */

static int cpuidle_latency_notify(struct notifier_block *b,

		unsigned long l, void *v)

{

	wake_up_all_idle_cpus();

	return NOTIFY_OK;

}



static struct notifier_block cpuidle_latency_notifier = {

	.notifier_call = cpuidle_latency_notify,

};



static inline void latency_notifier_init(struct notifier_block *n)

{

	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);

}



#else /* CONFIG_SMP */



#define latency_notifier_init(x) do { } while (0)



#endif /* CONFIG_SMP */



/**

 * cpuidle_init - core initializer

 */

static int __init cpuidle_init(void)

{

	int ret;



	if (cpuidle_disabled())

		return -ENODEV;



	ret = cpuidle_add_interface(cpu_subsys.dev_root);

	if (ret)

		return ret;



	latency_notifier_init(&cpuidle_latency_notifier);



	return 0;

	return cpuidle_add_interface(cpu_subsys.dev_root);

}



module_param(off, int, 0444);

include/linux/pm_qos.h

+0 −2
Original line number Diff line number Diff line
@@ -149,8 +149,6 @@ void pm_qos_update_request(struct pm_qos_request *req, 
void pm_qos_remove_request(struct pm_qos_request *req);



int pm_qos_request(int pm_qos_class);

int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier);

int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier);

int pm_qos_request_active(struct pm_qos_request *req);

s32 pm_qos_read_value(struct pm_qos_constraints *c);

kernel/power/qos.c

+11 −36
Original line number Diff line number Diff line
@@ -56,14 +56,12 @@ 
 */

static DEFINE_SPINLOCK(pm_qos_lock);



static BLOCKING_NOTIFIER_HEAD(cpu_dma_lat_notifier);

static struct pm_qos_constraints cpu_dma_constraints = {

	.list = PLIST_HEAD_INIT(cpu_dma_constraints.list),

	.target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,

	.default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,

	.no_constraint_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,

	.type = PM_QOS_MIN,

	.notifiers = &cpu_dma_lat_notifier,

};



/**
@@ -247,6 +245,14 @@ int pm_qos_request_active(struct pm_qos_request *req) 
}

EXPORT_SYMBOL_GPL(pm_qos_request_active);



static void cpu_latency_qos_update(struct pm_qos_request *req,

				   enum pm_qos_req_action action, s32 value)

{

	int ret = pm_qos_update_target(req->qos, &req->node, action, value);

	if (ret > 0)

		wake_up_all_idle_cpus();

}



/**

 * pm_qos_add_request - inserts new qos request into the list

 * @req: pointer to a preallocated handle
@@ -273,7 +279,7 @@ void pm_qos_add_request(struct pm_qos_request *req, 
	trace_pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY, value);



	req->qos = &cpu_dma_constraints;

	pm_qos_update_target(req->qos, &req->node, PM_QOS_ADD_REQ, value);

	cpu_latency_qos_update(req, PM_QOS_ADD_REQ, value);

}

EXPORT_SYMBOL_GPL(pm_qos_add_request);
@@ -302,7 +308,7 @@ void pm_qos_update_request(struct pm_qos_request *req, s32 new_value) 
	if (new_value == req->node.prio)

		return;



	pm_qos_update_target(req->qos, &req->node, PM_QOS_UPDATE_REQ, new_value);

	cpu_latency_qos_update(req, PM_QOS_UPDATE_REQ, new_value);

}

EXPORT_SYMBOL_GPL(pm_qos_update_request);
@@ -327,42 +333,11 @@ void pm_qos_remove_request(struct pm_qos_request *req) 


	trace_pm_qos_remove_request(PM_QOS_CPU_DMA_LATENCY, PM_QOS_DEFAULT_VALUE);



	pm_qos_update_target(req->qos, &req->node, PM_QOS_REMOVE_REQ,

			     PM_QOS_DEFAULT_VALUE);

	cpu_latency_qos_update(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);

	memset(req, 0, sizeof(*req));

}

EXPORT_SYMBOL_GPL(pm_qos_remove_request);



/**

 * pm_qos_add_notifier - sets notification entry for changes to target value

 * @pm_qos_class: Ignored.

 * @notifier: notifier block managed by caller.

 *

 * will register the notifier into a notification chain that gets called

 * upon changes to the PM_QOS_CPU_DMA_LATENCY target value.

 */

int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier)

{

	return blocking_notifier_chain_register(cpu_dma_constraints.notifiers,

						notifier);

}

EXPORT_SYMBOL_GPL(pm_qos_add_notifier);



/**

 * pm_qos_remove_notifier - deletes notification entry from chain.

 * @pm_qos_class: Ignored.

 * @notifier: notifier block to be removed.

 *

 * will remove the notifier from the notification chain that gets called

 * upon changes to the PM_QOS_CPU_DMA_LATENCY target value.

 */

int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)

{

	return blocking_notifier_chain_unregister(cpu_dma_constraints.notifiers,

						  notifier);

}

EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);



/* User space interface to global PM QoS via misc device. */



static int pm_qos_power_open(struct inode *inode, struct file *filp)

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