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    Subject[PATCH v2 3/4] drivers: dma-coherent: use MEMREMAP_WC for DMA_MEMORY_MAP
    Date
    When the DMA_MEMORY_MAP flag is used, memory which can be accessed
    directly should be returned, so use memremap(..., MEMREMAP_WC) to
    provide a writecombine mapping.

    Signed-off-by: Brian Starkey <brian.starkey@arm.com>
    Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
    ---
    drivers/base/dma-coherent.c | 20 ++++++++++++++++----
    1 file changed, 16 insertions(+), 4 deletions(-)

    diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
    index 87b8083..25bb398 100644
    --- a/drivers/base/dma-coherent.c
    +++ b/drivers/base/dma-coherent.c
    @@ -2,6 +2,7 @@
    * Coherent per-device memory handling.
    * Borrowed from i386
    */
    +#include <linux/io.h>
    #include <linux/slab.h>
    #include <linux/kernel.h>
    #include <linux/module.h>
    @@ -31,7 +32,10 @@ static bool dma_init_coherent_memory(
    if (!size)
    goto out;

    - mem_base = ioremap(phys_addr, size);
    + if (flags & DMA_MEMORY_MAP)
    + mem_base = memremap(phys_addr, size, MEMREMAP_WC);
    + else
    + mem_base = ioremap(phys_addr, size);
    if (!mem_base)
    goto out;

    @@ -54,8 +58,12 @@ static bool dma_init_coherent_memory(

    out:
    kfree(dma_mem);
    - if (mem_base)
    - iounmap(mem_base);
    + if (mem_base) {
    + if (flags & DMA_MEMORY_MAP)
    + memunmap(mem_base);
    + else
    + iounmap(mem_base);
    + }
    return false;
    }

    @@ -63,7 +71,11 @@ static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
    {
    if (!mem)
    return;
    - iounmap(mem->virt_base);
    +
    + if (mem->flags & DMA_MEMORY_MAP)
    + memunmap(mem->virt_base);
    + else
    + iounmap(mem->virt_base);
    kfree(mem->bitmap);
    kfree(mem);
    }
    --
    1.7.9.5
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