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PM: QoS: Drop PM_QOS_CPU_DMA_LATENCY notifier chain

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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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Tested-by: Amit Kucheria <amit.kucheria@linaro.org>
This commit is contained in:
Rafael J. Wysocki 2020-02-12 00:02:30 +01:00
parent 02c92a3789
commit 3a4a004222
3 changed files with 12 additions and 77 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
drivers/cpuidle/cpuidle.c
View File

@ -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);

2
include/linux/pm_qos.h
View File

@ -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);

47
kernel/power/qos.c
View File

@ -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)