[PATCH] arm: dma-mapping: fallback allocation for cma failure

[Gioh Kim]

If CMA is turned on and CMA size is set to zero, kernel should
behave as if CMA was not enabled at compile time.
Fallback allocation is added for CMA allocation failure.

Signed-off-by: Gioh Kim <gioh.kim@xxxxxxx>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
---
 arch/arm/mm/dma-mapping.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 18e98df..2a6c883 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -379,7 +379,7 @@ static int __init atomic_pool_init(void)
        unsigned long *bitmap;
        struct page *page;
        struct page **pages;
-       void *ptr;
+       void *ptr = NULL;
        int bitmap_size = BITS_TO_LONGS(nr_pages) * sizeof(long);

        bitmap = kzalloc(bitmap_size, GFP_KERNEL);
@@ -393,9 +393,10 @@ static int __init atomic_pool_init(void)
        if (IS_ENABLED(CONFIG_DMA_CMA))
                ptr = __alloc_from_contiguous(NULL, pool->size, prot, &page,
                                              atomic_pool_init);
-       else
+       if (!ptr)
                ptr = __alloc_remap_buffer(NULL, pool->size, gfp, prot, &page,
                                           atomic_pool_init);
+
        if (ptr) {
                int i;

@@ -703,8 +704,12 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
                addr = __alloc_from_pool(size, &page);
        else if (!IS_ENABLED(CONFIG_DMA_CMA))
                addr = __alloc_remap_buffer(dev, size, gfp, prot, &page, caller);
-       else
+       else {
                addr = __alloc_from_contiguous(dev, size, prot, &page, caller);
+               if (!addr)
+                       addr = __alloc_remap_buffer(dev, size, gfp, prot,
+                                                   &page, caller);
+       }

        if (addr)
                *handle = pfn_to_dma(dev, page_to_pfn(page));
--
1.7.9.5
--
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