2 files changed, 25 insertions, 1 deletions

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index 2ae842df4551..5c44dcb0987b 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -203,6 +203,13 @@ static inline void dma_free_writecombine(struct device *dev, size_t size,
 }
 
 /*
+ * This can be called during early boot to increase the size of the atomic
+ * coherent DMA pool above the default value of 256KiB. It must be called
+ * before postcore_initcall.
+ */
+extern void __init init_dma_coherent_pool_size(unsigned long size);
+
+/*
  * This can be called during boot to increase the size of the consistent
  * DMA region above it's default value of 2MB. It must be called before the
  * memory allocator is initialised, i.e. before any core_initcall.
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 4e7d1182e8a3..d1cc9c1d3566 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -267,6 +267,8 @@ static void __dma_free_remap(void *cpu_addr, size_t size)
         vunmap(cpu_addr);
 }
 
+#define DEFAULT_DMA_COHERENT_POOL_SIZE  SZ_256K
+
 struct dma_pool {
         size_t size;
         spinlock_t lock;
@@ -277,7 +279,7 @@ struct dma_pool {
 };
 
 static struct dma_pool atomic_pool = {
-        .size = SZ_256K,
+        .size = DEFAULT_DMA_COHERENT_POOL_SIZE,
 };
 
 static int __init early_coherent_pool(char *p)
@@ -287,6 +289,21 @@ static int __init early_coherent_pool(char *p)
 }
 early_param("coherent_pool", early_coherent_pool);
 
+void __init init_dma_coherent_pool_size(unsigned long size)
+{
+        /*
+         * Catch any attempt to set the pool size too late.
+         */
+        BUG_ON(atomic_pool.vaddr);
+
+        /*
+         * Set architecture specific coherent pool size only if
+         * it has not been changed by kernel command line parameter.
+         */
+        if (atomic_pool.size == DEFAULT_DMA_COHERENT_POOL_SIZE)
+                atomic_pool.size = size;
+}
+
 /*
  * Initialise the coherent pool for atomic allocations.
  */