DMA allocations might be subject to certain requirements specific to the
hardware using the buffers, such as availability of kernel mapping (for
contents fix-ups in the driver). The only entity that knows them is the
driver, so it must share this knowledge with vb2-dc.

This patch extends the alloc_ctx initialization interface to let the
driver specify DMA attrs, which are then stored inside the allocation
context and will be used for all allocations with that context.

As a side effect, all dma_*_coherent() calls are turned into
dma_*_attrs() calls, because the attributes need to be carried over
through all DMA operations.
Signed-off-by: NTomasz Figa <tfiga@chromium.org>
Signed-off-by: NDouglas Anderson <dianders@chromium.org>
Tested-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Acked-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>