MLK-11857 mxc IPUv3: PRE: Use spinlock to protect pre_list instead of mutex

The pre_list can be accessed in an irq context.  To avoid potential hang up
issue, use spinlock to protect pre_list instead of mutex.

Signed-off-by: Liu Ying <Ying.Liu@freescale.com>

diff --git a/drivers/mxc/ipu3/pre.c b/drivers/mxc/ipu3/pre.c
index 4f62377..0f30336 100644 (file)
--- a/drivers/mxc/ipu3/pre.c
+++ b/drivers/mxc/ipu3/pre.c
@@ -43,7 +43,7 @@ struct ipu_pre_data {
 };
 
 static LIST_HEAD(pre_list);
-static DEFINE_MUTEX(pre_list_lock);
+static DEFINE_SPINLOCK(pre_list_lock);
 
 static inline void pre_write(struct ipu_pre_data *pre,
                        u32 value, unsigned int offset)
@@ -59,15 +59,16 @@ static inline u32 pre_read(struct ipu_pre_data *pre, unsigned offset)
 static struct ipu_pre_data *get_pre(unsigned int id)
 {
        struct ipu_pre_data *pre;
+       unsigned long lock_flags;
 
-       mutex_lock(&pre_list_lock);
+       spin_lock_irqsave(&pre_list_lock, lock_flags);
        list_for_each_entry(pre, &pre_list, list) {
                if (pre->id == id) {
-                       mutex_unlock(&pre_list_lock);
+                       spin_unlock_irqrestore(&pre_list_lock, lock_flags);
                        return pre;
                }
        }
-       mutex_unlock(&pre_list_lock);
+       spin_unlock_irqrestore(&pre_list_lock, lock_flags);
 
        return NULL;
 }
@@ -885,6 +886,7 @@ static int ipu_pre_probe(struct platform_device *pdev)
        struct device_node *np = pdev->dev.of_node;
        struct ipu_pre_data *pre;
        struct resource *res;
+       unsigned long lock_flags;
        int id, irq, err;
 
        pre = devm_kzalloc(&pdev->dev, sizeof(*pre), GFP_KERNEL);
@@ -927,9 +929,9 @@ static int ipu_pre_probe(struct platform_device *pdev)
                return -ENOMEM;
        }
 
-       mutex_lock(&pre_list_lock);
+       spin_lock_irqsave(&pre_list_lock, lock_flags);
        list_add_tail(&pre->list, &pre_list);
-       mutex_unlock(&pre_list_lock);
+       spin_unlock_irqrestore(&pre_list_lock, lock_flags);
 
        ipu_pre_alloc_double_buffer(pre->id, IPU_PRE_MAX_WIDTH * 8 * IPU_PRE_MAX_BPP);
 
@@ -950,6 +952,7 @@ static int ipu_pre_probe(struct platform_device *pdev)
 static int ipu_pre_remove(struct platform_device *pdev)
 {
        struct ipu_pre_data *pre = platform_get_drvdata(pdev);
+       unsigned long lock_flags;
 
        if (pre->iram_pool && pre->double_buffer_base) {
                gen_pool_free(pre->iram_pool,
@@ -957,9 +960,9 @@ static int ipu_pre_remove(struct platform_device *pdev)
                              pre->double_buffer_size);
        }
 
-       mutex_lock(&pre_list_lock);
+       spin_lock_irqsave(&pre_list_lock, lock_flags);
        list_del(&pre->list);
-       mutex_unlock(&pre_list_lock);
+       spin_unlock_irqrestore(&pre_list_lock, lock_flags);
 
        return 0;
 }