linux-kernel - [PATCH v2] PM / OPP: discard duplicate OPP additions

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Date:	Fri, 16 May 2014 13:43:48 +0530
From:	Chander Kashyap <chander.kashyap@...aro.org>
To:	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	nm@...com, rjw@...ysocki.net, pavel@....cz, len.brown@...el.com,
	gregkh@...uxfoundation.org, viresh.kumar@...aro.org,
	Chander Kashyap <k.chander@...sung.com>,
	Inderpal Singh <inderpal.s@...sung.com>
Subject: [PATCH v2] PM / OPP: discard duplicate OPP additions

From: Chander Kashyap <k.chander@...sung.com>

It may be possible to unregister and re-register the cpufreq driver.
One such example is arm big-little IKS cpufreq driver. While
re-registering the driver, same OPPs may get added again.

This patch detects the duplicacy and discards them.

Signed-off-by: Chander Kashyap <k.chander@...sung.com>
Signed-off-by: Inderpal Singh <inderpal.s@...sung.com>
---
 Changes in v2:
	- Reorder check for duplicate opp

 drivers/base/power/opp.c |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index ca521e1..973da78 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -443,15 +443,24 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
 	new_opp->u_volt = u_volt;
 	new_opp->available = true;
 
-	/* Insert new OPP in order of increasing frequency */
+	/*
+	 * Insert new OPP in order of increasing frequency
+	 * and discard if already present
+	 */
 	head = &dev_opp->opp_list;
 	list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) {
-		if (new_opp->rate < opp->rate)
+		if (new_opp->rate <= opp->rate)
 			break;
 		else
 			head = &opp->node;
 	}
 
+	if (new_opp->rate == opp->rate) {
+		mutex_unlock(&dev_opp_list_lock);
+		kfree(new_opp);
+		return 0;
+	}
+
 	list_add_rcu(&new_opp->node, head);
 	mutex_unlock(&dev_opp_list_lock);
 
-- 
1.7.9.5

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