From 9525fd7f37b8d6c214fad960448f9e883cb48682 Mon Sep 17 00:00:00 2001
From: Seung-Woo Kim <sw0312.kim@samsung.com>
Date: Wed, 6 Feb 2013 13:21:14 +0900
Subject: [PATCH] --- yaml --- r: 358822 b: refs/heads/master c:
 60460abffc71523d65774f43ce1252972eeb0629 h: refs/heads/master v: v3

---
 [refs]                          |  2 +-
 trunk/arch/arm/Kconfig          | 21 +++++++++++++++++++++
 trunk/arch/arm/mm/dma-mapping.c |  3 +++
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 784e5d6287b7..ea1f8954c8c4 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f8669bef11fadfe811a5d7d59cb327499edac088
+refs/heads/master: 60460abffc71523d65774f43ce1252972eeb0629
diff --git a/trunk/arch/arm/Kconfig b/trunk/arch/arm/Kconfig
index 67874b82a4ed..4e89112b57e0 100644
--- a/trunk/arch/arm/Kconfig
+++ b/trunk/arch/arm/Kconfig
@@ -75,6 +75,27 @@ config ARM_DMA_USE_IOMMU
 	select ARM_HAS_SG_CHAIN
 	select NEED_SG_DMA_LENGTH
 
+if ARM_DMA_USE_IOMMU
+
+config ARM_DMA_IOMMU_ALIGNMENT
+	int "Maximum PAGE_SIZE order of alignment for DMA IOMMU buffers"
+	range 4 9
+	default 8
+	help
+	  DMA mapping framework by default aligns all buffers to the smallest
+	  PAGE_SIZE order which is greater than or equal to the requested buffer
+	  size. This works well for buffers up to a few hundreds kilobytes, but
+	  for larger buffers it just a waste of address space. Drivers which has
+	  relatively small addressing window (like 64Mib) might run out of
+	  virtual space with just a few allocations.
+
+	  With this parameter you can specify the maximum PAGE_SIZE order for
+	  DMA IOMMU buffers. Larger buffers will be aligned only to this
+	  specified order. The order is expressed as a power of two multiplied
+	  by the PAGE_SIZE.
+
+endif
+
 config HAVE_PWM
 	bool
 
diff --git a/trunk/arch/arm/mm/dma-mapping.c b/trunk/arch/arm/mm/dma-mapping.c
index 2163af4b31b8..6e2511561c3e 100644
--- a/trunk/arch/arm/mm/dma-mapping.c
+++ b/trunk/arch/arm/mm/dma-mapping.c
@@ -1029,6 +1029,9 @@ static inline dma_addr_t __alloc_iova(struct dma_iommu_mapping *mapping,
 	unsigned int count, start;
 	unsigned long flags;
 
+	if (order > CONFIG_ARM_DMA_IOMMU_ALIGNMENT)
+		order = CONFIG_ARM_DMA_IOMMU_ALIGNMENT;
+
 	count = ((PAGE_ALIGN(size) >> PAGE_SHIFT) +
 		 (1 << mapping->order) - 1) >> mapping->order;