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mmc: tmio_mmc: implement a bounce buffer for unaligned DMA

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For example, with SDIO WLAN cards, some transfers happen with buffers at
odd addresses, whereas the SH-Mobile DMA engine requires even addresses
for SDHI. This patch extends the tmio driver with a bounce buffer, that
is used for single entry scatter-gather lists both for sending and
receiving. If we ever encounter unaligned transfers with multi-element
sg lists, this patch will have to be extended. For now it just falls
back to PIO in this and other unsupported cases.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Guennadi Liakhovetski 2010-12-22 12:02:15 +01:00 • committed by Chris Ball
commit 93173054f2
2 changed files with 84 additions and 6 deletions
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include/linux/mfd/tmio.h
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@ -66,6 +66,7 @@ void tmio_core_mmc_clk_div(void __iomem *cnf, int shift, int state);
struct tmio_mmc_dma {
void *chan_priv_tx;
void *chan_priv_rx;
int alignment_shift;
};
/*