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Subject[PATCH v4 resend] PM / QoS: add pm_qos_update_request_timeout API
Date
The new API, pm_qos_update_request_timeout() is to provide a timeout
with pm_qos_update_request.

For example, pm_qos_update_request_timeout(req, 100, 1000), means that
QoS request on req with value 100 will be active for 1000 microseconds.
After 1000 microseconds, the QoS request thru req is reset. If there
were another pm_qos_update_request(req, x) during the 1000 us, this
new request with value x will override as this is another request on the
same req handle. A new request on the same req handle will always
override the previous request whether it is the conventional request or
it is the new timeout request.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Mark Gross <markgross@thegnar.org>

--
Resend v4
- Corrected changelog
Changes from v3
- The timeout value is expresses in us (1/1000000 sec), not ms (1/1000 sec).
Changes from v2
- Rebased to avoid merge conflict
Chages from v1(RFC)
- The semmantics of timeout changed. A timeout now means that the
corresponding qos-req object is being cancelled, not rolling back to
the qos request state at the time of API call. With this changes,
combined with the conventional update_request API, there exists up to
only one qos request per qos-req object.
- The timeout value is expressed in ms (1/1000 sec), not jiffies.
- Style changes, removing unnecessary changes.
- Bugfixes regarding pending timeout work.
---
include/linux/pm_qos.h | 4 +++
kernel/power/qos.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 54 insertions(+), 0 deletions(-)
diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index c8a541e..18689737 100644
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -8,6 +8,7 @@
#include <linux/notifier.h>
#include <linux/miscdevice.h>
#include <linux/device.h>
+#include <linux/workqueue.h>

enum {
PM_QOS_RESERVED = 0,
@@ -29,6 +30,7 @@ enum {
struct pm_qos_request {
struct plist_node node;
int pm_qos_class;
+ struct delayed_work work; /* for pm_qos_update_request_timeout */
};

struct dev_pm_qos_request {
@@ -73,6 +75,8 @@ 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,
s32 new_value);
+void pm_qos_update_request_timeout(struct pm_qos_request *req,
+ s32 new_value, unsigned long timeout_us);
void pm_qos_remove_request(struct pm_qos_request *req);

int pm_qos_request(int pm_qos_class);
diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index d6d6dbd..6a031e6 100644
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -230,6 +230,21 @@ int pm_qos_request_active(struct pm_qos_request *req)
EXPORT_SYMBOL_GPL(pm_qos_request_active);

/**
+ * pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
+ * @work: work struct for the delayed work (timeout)
+ *
+ * This cancels the timeout request by falling back to the default at timeout.
+ */
+static void pm_qos_work_fn(struct work_struct *work)
+{
+ struct pm_qos_request *req = container_of(to_delayed_work(work),
+ struct pm_qos_request,
+ work);
+
+ pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
+}
+
+/**
* pm_qos_add_request - inserts new qos request into the list
* @req: pointer to a preallocated handle
* @pm_qos_class: identifies which list of qos request to use
@@ -253,6 +268,7 @@ void pm_qos_add_request(struct pm_qos_request *req,
return;
}
req->pm_qos_class = pm_qos_class;
+ INIT_DELAYED_WORK(&req->work, pm_qos_work_fn);
pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
&req->node, PM_QOS_ADD_REQ, value);
}
@@ -279,6 +295,9 @@ void pm_qos_update_request(struct pm_qos_request *req,
return;
}

+ if (delayed_work_pending(&req->work))
+ cancel_delayed_work_sync(&req->work);
+
if (new_value != req->node.prio)
pm_qos_update_target(
pm_qos_array[req->pm_qos_class]->constraints,
@@ -287,6 +306,34 @@ void pm_qos_update_request(struct pm_qos_request *req,
EXPORT_SYMBOL_GPL(pm_qos_update_request);

/**
+ * pm_qos_update_request_timeout - modifies an existing qos request temporarily.
+ * @req : handle to list element holding a pm_qos request to use
+ * @new_value: defines the temporal qos request
+ * @timeout_us: the effective duration of this qos request in usecs.
+ *
+ * After timeout_us, this qos request is cancelled automatically.
+ */
+void pm_qos_update_request_timeout(struct pm_qos_request *req, s32 new_value,
+ unsigned long timeout_us)
+{
+ if (!req)
+ return;
+ if (WARN(!pm_qos_request_active(req),
+ "%s called for unknown object.", __func__))
+ return;
+
+ if (delayed_work_pending(&req->work))
+ cancel_delayed_work_sync(&req->work);
+
+ 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);
+
+ schedule_delayed_work(&req->work, usecs_to_jiffies(timeout_us));
+}
+
+/**
* pm_qos_remove_request - modifies an existing qos request
* @req: handle to request list element
*
@@ -305,6 +352,9 @@ void pm_qos_remove_request(struct pm_qos_request *req)
return;
}

+ if (delayed_work_pending(&req->work))
+ cancel_delayed_work_sync(&req->work);
+
pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
&req->node, PM_QOS_REMOVE_REQ,
PM_QOS_DEFAULT_VALUE);
--
1.7.4.1


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