[PATCH] arm: Improve MMC performance on Versatile Express

Wouldn't the ultimate solution be to simply use FIQs to service the
MMC FIFO?

The ultimate solution is to super-size FIFO ;-) It's not impossible (as the motherboard peripherals live in a FPGA), but according to our board people may be tricky due to the MMCI design (it's just ancient, that's all).

Now, the first thing I did was bumping the MMCI interrupts priorities, then I was considering use of FIQ. But - as Russell pointed out - it's simply not so simple...

the secure world could provide some kind of 
software based DMA engine facility to the non-secure world for this FIFO 
servicing purpose.

It's very, very unrealistic to expect any secure stack implementation (say, Visa or MasterCard authorization software) to provide such feature for anyone.

So - we'll try to enlarge FIFO. For the moment - playing with interrupts affinity seem to be a viable workaround.

Cheers!

Pawe?