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PM QoS: Generalize and export constraints management code
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In preparation for the per-device constratins support:
 - rename update_target to pm_qos_update_target
 - generalize and export pm_qos_update_target for usage by the upcoming
   per-device latency constraints framework:
   * operate on struct pm_qos_constraints for constraints management,
   * introduce an 'action' parameter for constraints add/update/remove,
   * the return value indicates if the aggregated constraint value has
     changed,
 - update the internal code to operate on struct pm_qos_constraints
 - add a NULL pointer check in the API functions

Signed-off-by: Jean Pihet <[email protected]>
Reviewed-by: Kevin Hilman <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
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Jean Pihet authored and rjwysocki committed Aug 25, 2011
1 parent 4e1779b commit abe98ec
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Showing 2 changed files with 81 additions and 56 deletions.
14 changes: 14 additions & 0 deletions include/linux/pm_qos.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,16 @@ struct pm_qos_constraints {
struct blocking_notifier_head *notifiers;
};

/* Action requested to pm_qos_update_target */
enum pm_qos_req_action {
PM_QOS_ADD_REQ, /* Add a new request */
PM_QOS_UPDATE_REQ, /* Update an existing request */
PM_QOS_REMOVE_REQ /* Remove an existing request */
};

#ifdef CONFIG_PM
int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
enum pm_qos_req_action action, int value);
void pm_qos_add_request(struct pm_qos_request *req, int pm_qos_class,
s32 value);
void pm_qos_update_request(struct pm_qos_request *req,
Expand All @@ -56,6 +65,11 @@ 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);
#else
static inline int pm_qos_update_target(struct pm_qos_constraints *c,
struct plist_node *node,
enum pm_qos_req_action action,
int value)
{ return 0; }
static inline void pm_qos_add_request(struct pm_qos_request *req,
int pm_qos_class, s32 value)
{ return; }
Expand Down
123 changes: 67 additions & 56 deletions kernel/power/qos.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -122,65 +122,91 @@ static const struct file_operations pm_qos_power_fops = {
};

/* unlocked internal variant */
static inline int pm_qos_get_value(struct pm_qos_object *o)
static inline int pm_qos_get_value(struct pm_qos_constraints *c)
{
if (plist_head_empty(&o->constraints->list))
return o->constraints->default_value;
if (plist_head_empty(&c->list))
return c->default_value;

switch (o->constraints->type) {
switch (c->type) {
case PM_QOS_MIN:
return plist_first(&o->constraints->list)->prio;
return plist_first(&c->list)->prio;

case PM_QOS_MAX:
return plist_last(&o->constraints->list)->prio;
return plist_last(&c->list)->prio;

default:
/* runtime check for not using enum */
BUG();
}
}

static inline s32 pm_qos_read_value(struct pm_qos_object *o)
static inline s32 pm_qos_read_value(struct pm_qos_constraints *c)
{
return o->constraints->target_value;
return c->target_value;
}

static inline void pm_qos_set_value(struct pm_qos_object *o, s32 value)
static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
{
o->constraints->target_value = value;
c->target_value = value;
}

static void update_target(struct pm_qos_object *o, struct plist_node *node,
int del, int value)
/**
* pm_qos_update_target - manages the constraints list and calls the notifiers
* if needed
* @c: constraints data struct
* @node: request to add to the list, to update or to remove
* @action: action to take on the constraints list
* @value: value of the request to add or update
*
* This function returns 1 if the aggregated constraint value has changed, 0
* otherwise.
*/
int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
enum pm_qos_req_action action, int value)
{
unsigned long flags;
int prev_value, curr_value;
int prev_value, curr_value, new_value;

spin_lock_irqsave(&pm_qos_lock, flags);
prev_value = pm_qos_get_value(o);
/* PM_QOS_DEFAULT_VALUE is a signal that the value is unchanged */
if (value != PM_QOS_DEFAULT_VALUE) {
prev_value = pm_qos_get_value(c);
if (value == PM_QOS_DEFAULT_VALUE)
new_value = c->default_value;
else
new_value = value;

switch (action) {
case PM_QOS_REMOVE_REQ:
plist_del(node, &c->list);
break;
case PM_QOS_UPDATE_REQ:
/*
* to change the list, we atomically remove, reinit
* with new value and add, then see if the extremal
* changed
*/
plist_del(node, &o->constraints->list);
plist_node_init(node, value);
plist_add(node, &o->constraints->list);
} else if (del) {
plist_del(node, &o->constraints->list);
} else {
plist_add(node, &o->constraints->list);
plist_del(node, &c->list);
case PM_QOS_ADD_REQ:
plist_node_init(node, new_value);
plist_add(node, &c->list);
break;
default:
/* no action */
;
}
curr_value = pm_qos_get_value(o);
pm_qos_set_value(o, curr_value);

curr_value = pm_qos_get_value(c);
pm_qos_set_value(c, curr_value);

spin_unlock_irqrestore(&pm_qos_lock, flags);

if (prev_value != curr_value)
blocking_notifier_call_chain(o->constraints->notifiers,
if (prev_value != curr_value) {
blocking_notifier_call_chain(c->notifiers,
(unsigned long)curr_value,
NULL);
return 1;
} else {
return 0;
}
}

/**
Expand All @@ -191,7 +217,7 @@ static void update_target(struct pm_qos_object *o, struct plist_node *node,
*/
int pm_qos_request(int pm_qos_class)
{
return pm_qos_read_value(pm_qos_array[pm_qos_class]);
return pm_qos_read_value(pm_qos_array[pm_qos_class]->constraints);
}
EXPORT_SYMBOL_GPL(pm_qos_request);

Expand All @@ -217,20 +243,16 @@ EXPORT_SYMBOL_GPL(pm_qos_request_active);
void pm_qos_add_request(struct pm_qos_request *req,
int pm_qos_class, s32 value)
{
struct pm_qos_object *o = pm_qos_array[pm_qos_class];
int new_value;
if (!req) /*guard against callers passing in null */
return;

if (pm_qos_request_active(req)) {
WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
return;
}
if (value == PM_QOS_DEFAULT_VALUE)
new_value = o->constraints->default_value;
else
new_value = value;
plist_node_init(&req->node, new_value);
req->pm_qos_class = pm_qos_class;
update_target(o, &req->node, 0, PM_QOS_DEFAULT_VALUE);
pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
&req->node, PM_QOS_ADD_REQ, value);
}
EXPORT_SYMBOL_GPL(pm_qos_add_request);

Expand All @@ -247,9 +269,6 @@ EXPORT_SYMBOL_GPL(pm_qos_add_request);
void pm_qos_update_request(struct pm_qos_request *req,
s32 new_value)
{
s32 temp;
struct pm_qos_object *o;

if (!req) /*guard against callers passing in null */
return;

Expand All @@ -258,15 +277,10 @@ void pm_qos_update_request(struct pm_qos_request *req,
return;
}

o = pm_qos_array[req->pm_qos_class];

if (new_value == PM_QOS_DEFAULT_VALUE)
temp = o->constraints->default_value;
else
temp = new_value;

if (temp != req->node.prio)
update_target(o, &req->node, 0, temp);
if (new_value != req->node.prio)
pm_qos_update_target(
pm_qos_array[req->pm_qos_class]->constraints,
&req->node, PM_QOS_UPDATE_REQ, new_value);
}
EXPORT_SYMBOL_GPL(pm_qos_update_request);

Expand All @@ -280,9 +294,7 @@ EXPORT_SYMBOL_GPL(pm_qos_update_request);
*/
void pm_qos_remove_request(struct pm_qos_request *req)
{
struct pm_qos_object *o;

if (req == NULL)
if (!req) /*guard against callers passing in null */
return;
/* silent return to keep pcm code cleaner */

Expand All @@ -291,8 +303,9 @@ void pm_qos_remove_request(struct pm_qos_request *req)
return;
}

o = pm_qos_array[req->pm_qos_class];
update_target(o, &req->node, 1, PM_QOS_DEFAULT_VALUE);
pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
&req->node, PM_QOS_REMOVE_REQ,
PM_QOS_DEFAULT_VALUE);
memset(req, 0, sizeof(*req));
}
EXPORT_SYMBOL_GPL(pm_qos_remove_request);
Expand Down Expand Up @@ -396,17 +409,15 @@ static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
{
s32 value;
unsigned long flags;
struct pm_qos_object *o;
struct pm_qos_request *req = filp->private_data;

if (!req)
return -EINVAL;
if (!pm_qos_request_active(req))
return -EINVAL;

o = pm_qos_array[req->pm_qos_class];
spin_lock_irqsave(&pm_qos_lock, flags);
value = pm_qos_get_value(o);
value = pm_qos_get_value(pm_qos_array[req->pm_qos_class]->constraints);
spin_unlock_irqrestore(&pm_qos_lock, flags);

return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));
Expand Down

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