The original arm implementation uses dmac_map_area which is not
portable. Replace it with an architecture neutral version
which uses dma_map_sg.
As you can see that for larger page sizes, the dma_map_sg
implementation is faster then the original unportable dma_map_area
implementation.
Test dmac_map_area dma_map_page dma_map_sg
vchiq_test -b 4 10000 51us/iter 76us/iter 76us
vchiq_test -b 8 10000 70us/iter 82us/iter 91us
vchiq_test -b 16 10000 94us/iter 118us/iter 121us
vchiq_test -b 32 10000 146us/iter 173us/iter 187us
vchiq_test -b 64 10000 263us/iter 328us/iter 299us
vchiq_test -b 128 10000 529us/iter 631us/iter 595us
vchiq_test -b 256 10000 2285us/iter 2275us/iter 2001us
vchiq_test -b 512 10000 4372us/iter 4616us/iter 4123us
For message sizes >= 64KB, dma_map_sg is faster then dma_map_page.
For message size >= 256KB, the dma_map_sg is the fastest
implementation.
"Normal" messages sizes should be about 1MB which is beyond
the length that this change shows a speed increase.
This is v2 of the patch which includes extra WARN_ONs and
incorporates feedback from Eric Anholt <eric@anholt.net>.
Signed-off-by: Michael Zoran <mzoran@crowfest.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Michael Zoran
cf9caf1929