The mmci host driver implementation for double buffering is not intended nor ready for mainline yet. It is only an example of how to implement pre_req() and post_req(). The reason for this is that the basic DMA support for MMCI is not complete yet.
This patch series depends on "[PATCH 0/5] mmc: add double buffering for mmc block requests"
Linus Walleij (1): mmci: add PrimeCell generic DMA to MMCI/PL180
Per Forlin (1): ARM: mmci: add support for double buffering
Ulf Hansson (2): mmci: fixup broken_blockend variant patch MMCI: Corrections for DMA
drivers/mmc/host/mmci.c | 538 ++++++++++++++++++++++++++++++++++++++------- drivers/mmc/host/mmci.h | 21 ++- include/linux/amba/mmci.h | 16 ++ 3 files changed, 496 insertions(+), 79 deletions(-)