ARM: 8398/1: arm DMA: Fix allocation from CMA for coherent DMA

This patch allows the use of CMA for DMA coherent memory allocation.
At the moment if the input parameter "is_coherent" is set to true
the allocation is not made using the CMA, which I think is not the
desired behaviour.
The patch covers the allocation and free of memory for coherent
DMA.

Signed-off-by: Lorenzo Nava <lorenx4@gmail.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 12 insertions, 9 deletions

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 5edf17cf043d..ad7419e69967 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -649,14 +649,18 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
         size = PAGE_ALIGN(size);
         want_vaddr = !dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, attrs);
 
-        if (is_coherent || nommu())
+        if (nommu())
+                addr = __alloc_simple_buffer(dev, size, gfp, &page);
+        else if (dev_get_cma_area(dev) && (gfp & __GFP_WAIT))
+                addr = __alloc_from_contiguous(dev, size, prot, &page,
+                                               caller, want_vaddr);
+        else if (is_coherent)
                 addr = __alloc_simple_buffer(dev, size, gfp, &page);
         else if (!(gfp & __GFP_WAIT))
                 addr = __alloc_from_pool(size, &page);
-        else if (!dev_get_cma_area(dev))
-                addr = __alloc_remap_buffer(dev, size, gfp, prot, &page, caller, want_vaddr);
         else
-                addr = __alloc_from_contiguous(dev, size, prot, &page, caller, want_vaddr);
+                addr = __alloc_remap_buffer(dev, size, gfp, prot, &page,
+                                            caller, want_vaddr);
 
         if (page)
                 *handle = pfn_to_dma(dev, page_to_pfn(page));
@@ -684,13 +688,12 @@ void *arm_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
 static void *arm_coherent_dma_alloc(struct device *dev, size_t size,
         dma_addr_t *handle, gfp_t gfp, struct dma_attrs *attrs)
 {
-        pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL);
         void *memory;
 
         if (dma_alloc_from_coherent(dev, size, handle, &memory))
                 return memory;
 
-        return __dma_alloc(dev, size, handle, gfp, prot, true,
+        return __dma_alloc(dev, size, handle, gfp, PAGE_KERNEL, true,
                            attrs, __builtin_return_address(0));
 }
 
@@ -754,12 +757,12 @@ static void __arm_dma_free(struct device *dev, size_t size, void *cpu_addr,
 
         size = PAGE_ALIGN(size);
 
-        if (is_coherent || nommu()) {
+        if (nommu()) {
                 __dma_free_buffer(page, size);
-        } else if (__free_from_pool(cpu_addr, size)) {
+        } else if (!is_coherent && __free_from_pool(cpu_addr, size)) {
                 return;
         } else if (!dev_get_cma_area(dev)) {
-                if (want_vaddr)
+                if (want_vaddr && !is_coherent)
                         __dma_free_remap(cpu_addr, size);
                 __dma_free_buffer(page, size);
         } else {