ARM: DMA-Mapping: add function for setting coherent pool size from pl…

…atform code Some platforms might require to increase atomic coherent pool to make sure that their device will be able to allocate all their buffers from atomic context. This function can be also used to decrease atomic coherent pool size if coherent allocations are not used for the given sub-platform. Suggested-by: Josh Coombs <[email protected]> Signed-off-by: Marek Szyprowski <[email protected]>
pidodo · Aug 28, 2012 · 6e5267a · 6e5267a
1 parent e092705
commit 6e5267a
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Showing 2 changed files with 25 additions and 1 deletion.
diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
@@ -202,6 +202,13 @@ static inline void dma_free_writecombine(struct device *dev, size_t size,
 	return dma_free_attrs(dev, size, cpu_addr, dma_handle, &attrs);
 }
 
+/*
+ * 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

diff --git 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.
  */