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From:   Lukasz Luba <l.luba@partner.samsung.com>
To:     linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Cc:     b.zolnierkie@samsung.com, myungjoo.ham@samsung.com,
        cw00.choi@samsung.com, kyungmin.park@samsung.com,
        m.szyprowski@samsung.com, s.nawrocki@samsung.com, tkjos@google.com,
        joel@joelfernandes.org, chris.diamand@arm.com, mka@chromium.org,
        Lukasz Luba <l.luba@partner.samsung.com>
Subject: [PATCH v2 1/2] drivers: devfreq: change devfreq workqueue mechanism
Date:   Mon, 11 Feb 2019 16:30:04 +0100
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        <CGME20190211153035eucas1p12ecdd3289a20ce9fb28588ba20869c60@eucas1p1.samsung.com>
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There is no need for creating another workqueue in the system,
the existing one should meet the requirements.
This patch removes devfreq's custom workqueue and uses system one.
It switches from queue_delayed_work() to schedule_delayed_work().
It also does not wake up the system when it enters suspend (this
functionality stays the same).

Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
---
 drivers/devfreq/devfreq.c | 25 ++++++-------------------
 1 file changed, 6 insertions(+), 19 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 0ae3de7..882e717 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -31,13 +31,6 @@
 
 static struct class *devfreq_class;
 
-/*
- * devfreq core provides delayed work based load monitoring helper
- * functions. Governors can use these or can implement their own
- * monitoring mechanism.
- */
-static struct workqueue_struct *devfreq_wq;
-
 /* The list of all device-devfreq governors */
 static LIST_HEAD(devfreq_governor_list);
 /* The list of all device-devfreq */
@@ -391,8 +384,8 @@ static void devfreq_monitor(struct work_struct *work)
 	if (err)
 		dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
 
-	queue_delayed_work(devfreq_wq, &devfreq->work,
-				msecs_to_jiffies(devfreq->profile->polling_ms));
+	schedule_delayed_work(&devfreq->work,
+			      msecs_to_jiffies(devfreq->profile->polling_ms));
 	mutex_unlock(&devfreq->lock);
 }
 
@@ -409,7 +402,7 @@ void devfreq_monitor_start(struct devfreq *devfreq)
 {
 	INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
 	if (devfreq->profile->polling_ms)
-		queue_delayed_work(devfreq_wq, &devfreq->work,
+		schedule_delayed_work(&devfreq->work,
 			msecs_to_jiffies(devfreq->profile->polling_ms));
 }
 EXPORT_SYMBOL(devfreq_monitor_start);
@@ -473,7 +466,7 @@ void devfreq_monitor_resume(struct devfreq *devfreq)
 
 	if (!delayed_work_pending(&devfreq->work) &&
 			devfreq->profile->polling_ms)
-		queue_delayed_work(devfreq_wq, &devfreq->work,
+		schedule_delayed_work(&devfreq->work,
 			msecs_to_jiffies(devfreq->profile->polling_ms));
 
 	devfreq->last_stat_updated = jiffies;
@@ -516,7 +509,7 @@ void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 
 	/* if current delay is zero, start polling with new delay */
 	if (!cur_delay) {
-		queue_delayed_work(devfreq_wq, &devfreq->work,
+		schedule_delayed_work(&devfreq->work,
 			msecs_to_jiffies(devfreq->profile->polling_ms));
 		goto out;
 	}
@@ -527,7 +520,7 @@ void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
 		cancel_delayed_work_sync(&devfreq->work);
 		mutex_lock(&devfreq->lock);
 		if (!devfreq->stop_polling)
-			queue_delayed_work(devfreq_wq, &devfreq->work,
+			schedule_delayed_work(&devfreq->work,
 			      msecs_to_jiffies(devfreq->profile->polling_ms));
 	}
 out:
@@ -1430,12 +1423,6 @@ static int __init devfreq_init(void)
 		return PTR_ERR(devfreq_class);
 	}
 
-	devfreq_wq = create_freezable_workqueue("devfreq_wq");
-	if (!devfreq_wq) {
-		class_destroy(devfreq_class);
-		pr_err("%s: couldn't create workqueue\n", __FILE__);
-		return -ENOMEM;
-	}
 	devfreq_class->dev_groups = devfreq_groups;
 
 	return 0;
-- 
2.7.4