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SubjectRe: [PATCH 1/5] MIPS: HIGHMEM DMA on noncoherent MIPS32 processors
Hello.

On 07-09-2010 8:03, Kevin Cernekee wrote:

> The MIPS DMA coherency functions do not work properly (i.e. kernel oops)
> when HIGHMEM pages are passed in as arguments. This patch uses the PPC
> approach of calling kmap_atomic() with IRQs disabled to temporarily map
> high pages, in order to flush them out to memory.

> Signed-off-by: Dezhong Diao <dediao@cisco.com>
> Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
> ---
> arch/mips/mm/dma-default.c | 159 ++++++++++++++++++++++----------------------
> 1 files changed, 80 insertions(+), 79 deletions(-)

> diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
> index 469d401..3f23952 100644
> --- a/arch/mips/mm/dma-default.c
> +++ b/arch/mips/mm/dma-default.c
[...]
> @@ -191,8 +231,8 @@ void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
> enum dma_data_direction direction)
> {
> if (cpu_is_noncoherent_r10000(dev))
> - __dma_sync(dma_addr_to_virt(dev, dma_addr), size,
> - direction);
> + __dma_sync(dma_addr_to_page(dev, dma_addr),
> + (dma_addr & ~PAGE_MASK), size, direction);

Parens are not needed here.

> @@ -277,15 +297,10 @@ EXPORT_SYMBOL(dma_sync_single_for_cpu);
> void dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle,
> size_t size, enum dma_data_direction direction)
> {
> - BUG_ON(direction == DMA_NONE);
> -
> plat_extra_sync_for_device(dev);
> - if (!plat_device_is_coherent(dev)) {
> - unsigned long addr;
> -
> - addr = dma_addr_to_virt(dev, dma_handle);
> - __dma_sync(addr, size, direction);
> - }
> + if (!plat_device_is_coherent(dev))
> + __dma_sync(dma_addr_to_page(dev, dma_handle),
> + (dma_handle & ~PAGE_MASK), size, direction);

Here as well...

WBR, Sergei


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