[PATCH] mmci: restrict DMA usage to large, even multiblock transfers

[Linus Walleij]

2011/2/1 Russell King - ARM Linux <linux at arm.linux.org.uk>:

> So... I think this patch will work fine on ST variants, returning the
> DMA request signals back to their classic meaning.  That being LSREQ
> is only activated on the _final_ transfer rather than the last 8
> transfers, which as Linus describes makes your DMA controller complete
> on the 8th-to-last transfer.

I've tested this patch on MMC and SD on U8500 and it works
fine, so
Tested-by: Linus Walleij <linus.walleij at linaro.org>

However I think this weird bit turning off all single requests
is there for some reason and I still try to find out what the
usecase really is. I highly suspect that it's related to either
doing some SDIO usecase or pleasing some buggy DMA
controller.

Having it deactivated most likely works for all MMC/SD cards
and then we have to think about having (ST-Specific)
if (mmc_card_sdio()) clauses for SDIO usecases, which we
can defer until we know what's going on.

Yours,
Linus Walleij