ARC: don't check for HIGHMEM pages in arch_dma_alloc

__GFP_HIGHMEM flag is cleared by upper layer functions
(in include/linux/dma-mapping.h) so we'll never get a
__GFP_HIGHMEM flag in arch_dma_alloc gfp argument.
That's why alloc_pages will never return highmem page
here.

Get rid of highmem pages handling and cleanup arch_dma_alloc
and arch_dma_free functions.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
index c0b4939..c75d5c3 100644 (file)
--- a/arch/arc/mm/dma.c
+++ b/arch/arc/mm/dma.c
@@ -24,30 +24,29 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
        struct page *page;
        phys_addr_t paddr;
        void *kvaddr;
-       int need_coh = 1, need_kvaddr = 0;
+       bool need_coh = !(attrs & DMA_ATTR_NON_CONSISTENT);
+
+       /*
+        * __GFP_HIGHMEM flag is cleared by upper layer functions
+        * (in include/linux/dma-mapping.h) so we should never get a
+        * __GFP_HIGHMEM here.
+        */
+       BUG_ON(gfp & __GFP_HIGHMEM);
 
        page = alloc_pages(gfp, order);
        if (!page)
                return NULL;
 
-       if (attrs & DMA_ATTR_NON_CONSISTENT)
-               need_coh = 0;
-
-       /*
-        * - A coherent buffer needs MMU mapping to enforce non-cachability
-        * - A highmem page needs a virtual handle (hence MMU mapping)
-        *   independent of cachability
-        */
-       if (PageHighMem(page) || need_coh)
-               need_kvaddr = 1;
-
        /* This is linear addr (0x8000_0000 based) */
        paddr = page_to_phys(page);
 
        *dma_handle = paddr;
 
-       /* This is kernel Virtual address (0x7000_0000 based) */
-       if (need_kvaddr) {
+       /*
+        * A coherent buffer needs MMU mapping to enforce non-cachability.
+        * kvaddr is kernel Virtual address (0x7000_0000 based).
+        */
+       if (need_coh) {
                kvaddr = ioremap_nocache(paddr, size);
                if (kvaddr == NULL) {
                        __free_pages(page, order);
@@ -78,11 +77,8 @@ void arch_dma_free(struct device *dev, size_t size, void *vaddr,
 {
        phys_addr_t paddr = dma_handle;
        struct page *page = virt_to_page(paddr);
-       int is_non_coh = 1;
-
-       is_non_coh = (attrs & DMA_ATTR_NON_CONSISTENT);
 
-       if (PageHighMem(page) || !is_non_coh)
+       if (!(attrs & DMA_ATTR_NON_CONSISTENT))
                iounmap((void __force __iomem *)vaddr);
 
        __free_pages(page, get_order(size));