mmc: alcor: enable DMA transfer of large buffers

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DMA on this hardware is limited to dealing with a single page at a
time. Previously, the driver was set up accordingly to request single-page
DMA buffers, however that had the effect of generating a large number
of small MMC requests for data I/O.

Improve the driver to accept scatter-gather DMA buffers of larger sizes.
Iterate through those buffers a page at a time.

Testing with dd, this increases write performance from 2mb/sec to
10mb/sec, and increases read performance from 4mb/sec to 14mb/sec.

Signed-off-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

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Daniel Drake 2019-04-01 13:42:15 +08:00 • committed by Ulf Hansson

parent e374e87538

commit c278150e0d

1 changed files with 35 additions and 53 deletions

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88

drivers/mmc/host/alcor.c

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