Date: Mon, 07 Oct 2013 10:58:18 +0900
From: Cho KyongHo <pullip.cho@samsung.com>
To: Linux ARM Kernel <linux-arm-kernel@lists.infradead.org>,
        Linux DeviceTree <devicetree@vger.kernel.org>,
        Linux IOMMU <iommu@lists.linux-foundation.org>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Linux Samsung SOC <linux-samsung-soc@vger.kernel.org>
Cc: Antonios Motakis <a.motakis@virtualopensystems.com>,
        Grant Grundler <grundler@chromium.org>, Joerg Roedel <joro@8bytes.org>,
        Kukjin Kim <kgene.kim@samsung.com>,
        Prathyush <prathyush.k@samsung.com>,
        Rahul Sharma <rahul.sharma@samsung.com>,
        Sachin Kamat <sachin.kamat@linaro.org>,
        Subash Patel <supash.ramaswamy@linaro.org>,
        Varun Sethi <Varun.Sethi@freescale.com>,
        Sylwester Nawrocki <s.nawrocki@samsung.com>,
        Tomasz Figa <t.figa@samsung.com>
Subject: [PATCH v10 18/20] iommu/exynos: change rwlock to spinlock
Message-id: <20131007105818.916595496f5fa52c5bf372bf@samsung.com>
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Since acquiring read_lock is not more frequent than write_lock, it is
not beneficial to use rwlock, this commit changes rwlock to spinlock.

Reviewed-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>
---
 drivers/iommu/exynos-iommu.c |   35 ++++++++++++++++++-----------------
 1 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index e48c2fb..26ba554 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -183,7 +183,7 @@ struct sysmmu_drvdata {
 	struct clk *clk;
 	struct clk *clk_master;
 	int activations;
-	rwlock_t lock;
+	spinlock_t lock;
 	struct iommu_domain *domain;
 	bool runtime_active;
 	unsigned long pgtable;
@@ -298,11 +298,12 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
 	unsigned long addr = -1;
 	int ret = -ENOSYS;
 
-	read_lock(&data->lock);
-
 	WARN_ON(!is_sysmmu_active(data));
 
 	clk_enable(data->clk_master);
+
+	spin_lock(&data->lock);
+
 	itype = (enum exynos_sysmmu_inttype)
 		__ffs(__raw_readl(data->sfrbase + REG_INT_STATUS));
 	if (WARN_ON(!((itype >= 0) && (itype < SYSMMU_FAULT_UNKNOWN))))
@@ -335,7 +336,7 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
 
 	clk_disable(data->clk_master);
 
-	read_unlock(&data->lock);
+	spin_unlock(&data->lock);
 
 	return IRQ_HANDLED;
 }
@@ -356,7 +357,7 @@ static bool __sysmmu_disable(struct sysmmu_drvdata *data)
 	bool disabled;
 	unsigned long flags;
 
-	write_lock_irqsave(&data->lock, flags);
+	spin_lock_irqsave(&data->lock, flags);
 
 	disabled = set_sysmmu_inactive(data);
 
@@ -373,7 +374,7 @@ static bool __sysmmu_disable(struct sysmmu_drvdata *data)
 					data->activations);
 	}
 
-	write_unlock_irqrestore(&data->lock, flags);
+	spin_unlock_irqrestore(&data->lock, flags);
 
 	return disabled;
 }
@@ -421,7 +422,7 @@ static int __sysmmu_enable(struct sysmmu_drvdata *data,
 	int ret = 0;
 	unsigned long flags;
 
-	write_lock_irqsave(&data->lock, flags);
+	spin_lock_irqsave(&data->lock, flags);
 	if (set_sysmmu_active(data)) {
 		data->pgtable = pgtable;
 		data->domain = domain;
@@ -439,7 +440,7 @@ static int __sysmmu_enable(struct sysmmu_drvdata *data,
 	if (WARN_ON(ret < 0))
 		set_sysmmu_inactive(data); /* decrement count */
 
-	write_unlock_irqrestore(&data->lock, flags);
+	spin_unlock_irqrestore(&data->lock, flags);
 
 	return ret;
 }
@@ -503,7 +504,7 @@ static void sysmmu_tlb_invalidate_entry(struct device *dev, unsigned long iova,
 
 	data = dev_get_drvdata(client->sysmmu);
 
-	read_lock_irqsave(&data->lock, flags);
+	spin_lock_irqsave(&data->lock, flags);
 	if (is_sysmmu_active(data) && data->runtime_active) {
 		unsigned int num_inv = 1;
 		/*
@@ -526,7 +527,7 @@ static void sysmmu_tlb_invalidate_entry(struct device *dev, unsigned long iova,
 		dev_dbg(dev, "disabled. Skipping TLB invalidation @ %#lx\n",
 			iova);
 	}
-	read_unlock_irqrestore(&data->lock, flags);
+	spin_unlock_irqrestore(&data->lock, flags);
 }
 
 void exynos_sysmmu_tlb_invalidate(struct device *dev)
@@ -537,7 +538,7 @@ void exynos_sysmmu_tlb_invalidate(struct device *dev)
 
 	data = dev_get_drvdata(client->sysmmu);
 
-	read_lock_irqsave(&data->lock, flags);
+	spin_lock_irqsave(&data->lock, flags);
 	if (is_sysmmu_active(data) && data->runtime_active) {
 		clk_enable(data->clk_master);
 		if (sysmmu_block(data->sfrbase)) {
@@ -548,7 +549,7 @@ void exynos_sysmmu_tlb_invalidate(struct device *dev)
 	} else {
 		dev_dbg(dev, "disabled. Skipping TLB invalidation\n");
 	}
-	read_unlock_irqrestore(&data->lock, flags);
+	spin_unlock_irqrestore(&data->lock, flags);
 }
 
 static int __init exynos_sysmmu_probe(struct platform_device *pdev)
@@ -609,7 +610,7 @@ static int __init exynos_sysmmu_probe(struct platform_device *pdev)
 	}
 
 	data->sysmmu = dev;
-	rwlock_init(&data->lock);
+	spin_lock_init(&data->lock);
 
 	platform_set_drvdata(pdev, data);
 
@@ -625,11 +626,11 @@ static int sysmmu_suspend(struct device *dev)
 {
 	struct sysmmu_drvdata *data = dev_get_drvdata(dev);
 	unsigned long flags;
-	read_lock_irqsave(&data->lock, flags);
+	spin_lock_irqsave(&data->lock, flags);
 	if (is_sysmmu_active(data) &&
 		(!pm_runtime_enabled(dev) || data->runtime_active))
 		__sysmmu_disable_nocount(data);
-	read_unlock_irqrestore(&data->lock, flags);
+	spin_unlock_irqrestore(&data->lock, flags);
 	return 0;
 }
 
@@ -637,11 +638,11 @@ static int sysmmu_resume(struct device *dev)
 {
 	struct sysmmu_drvdata *data = dev_get_drvdata(dev);
 	unsigned long flags;
-	read_lock_irqsave(&data->lock, flags);
+	spin_lock_irqsave(&data->lock, flags);
 	if (is_sysmmu_active(data) &&
 		(!pm_runtime_enabled(dev) || data->runtime_active))
 		__sysmmu_enable_nocount(data);
-	read_unlock_irqrestore(&data->lock, flags);
+	spin_unlock_irqrestore(&data->lock, flags);
 	return 0;
 }
 #endif
-- 
1.7.2.5

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