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:

quoted

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 <redacted>

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