strictly order DMA from a device across all intervening busses and
bridges. This barrier is not specific to a particular type of
interconnect, it applies to the system as a whole, and so its
-implementation must account for the idiosyncracies of the system all
+implementation must account for the idiosyncrasies of the system all
the way from the DMA device to memory.
As an example of a situation where DMA_ATTR_WRITE_BARRIER would be
Buffers allocated with this attribute can be only passed to user space
by calling dma_mmap_attrs(). By using this API, you are guaranteeing
that you won't dereference the pointer returned by dma_alloc_attr(). You
-can threat it as a cookie that must be passed to dma_mmap_attrs() and
+can treat it as a cookie that must be passed to dma_mmap_attrs() and
dma_free_attrs(). Make sure that both of these also get this attribute
set on each call.
(usually it means that the cache has been flushed or invalidated
depending on the dma direction). However, next calls to
dma_map_{single,page,sg}() for other devices will perform exactly the
-same sychronization operation on the CPU cache. CPU cache sychronization
+same synchronization operation on the CPU cache. CPU cache synchronization
might be a time consuming operation, especially if the buffers are
large, so it is highly recommended to avoid it if possible.
DMA_ATTR_SKIP_CPU_SYNC allows platform code to skip synchronization of
dma_unmap_{single,page,sg} functions family to force buffer to stay in
device domain after releasing a mapping for it. Use this attribute with
care!
+
+DMA_ATTR_FORCE_CONTIGUOUS
+-------------------------
+
+By default DMA-mapping subsystem is allowed to assemble the buffer
+allocated by dma_alloc_attrs() function from individual pages if it can
+be mapped as contiguous chunk into device dma address space. By
+specifing this attribute the allocated buffer is forced to be contiguous
+also in physical memory.