Error handling of the dma_map_single and dma_map_page APIs is a little
problematic at the moment, in that we use different encodings in the
returned dma_addr_t to indicate an error. That means we require an
additional indirect call to figure out if a dma mapping call returned
an error, and a lot of boilerplate code to implement these semantics.
Instead return the maximum addressable value as the error. As long
as we don't allow mapping single-byte ranges with single-byte alignment
this value can never be a valid return. Additionaly if drivers do
not check the return value from the dma_map* routines this values means
they will generally not be pointed to actual memory.
Once the default value is added here we can start removing the
various mapping_error methods and just rely on this generic check.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Acked-by: Russell King <rmk+kernel@armlinux.org.uk> Acked-by: Linus Torvalds <torvalds@linux-foundation.org>