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    SubjectRE: [Linaro-mm-sig] [PATCHv2 1/6] common: DMA-mapping: add DMA_ATTR_NO_KERNEL_MAPPING attribute
    Date
    Hello,

    On Wednesday, June 13, 2012 8:52 PM Daniel Vetter wrote:

    > On Wed, Jun 13, 2012 at 01:50:13PM +0200, Marek Szyprowski wrote:
    > > This patch adds DMA_ATTR_NO_KERNEL_MAPPING attribute which lets the
    > > platform to avoid creating a kernel virtual mapping for the allocated
    > > buffer. On some architectures creating such mapping is non-trivial task
    > > and consumes very limited resources (like kernel virtual address space
    > > or dma consistent address space). Buffers allocated with this attribute
    > > can be only passed to user space by calling dma_mmap_attrs().
    > >
    > > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
    > > Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
    >
    > Looks like a nice little extension to support dma-buf for the common case,
    > so:
    >
    > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
    >
    > One question is whether we should go right ahead and add kmap support for
    > this, too (with a default implementation that simply returns a pointer to
    > the coherent&contigous dma mem), but I guess that can wait until a
    > use-case pops up.

    I will wait with this until there will be real use cases. Let's get the
    patch into mainline first.

    Best regards
    --
    Marek Szyprowski
    Samsung Poland R&D Center




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