Re: [PATCH RFC 0/2] mmc: jz4740: Use the integrated DMA controller on the X1600

[Olivier Louvignes]

Hi Ulf,

Please drop this RFC, both its premise and its question turned out to
be wrong.

The X1600's MSCs do have request lines to the system DMA controller:
the programming manual lists PDMA request types for both (0x34 to 0x37),
and MSC_DMAC.DMASEL picks between the two DMA paths. With dmas in the
device tree, the existing PDMA path works on the HiBy R1, card setup
included, and reads as fast as the integrated DMA did (23.0 to 23.5 MB/s
against 23.5 MB/s with dd, the CPU about 20% busy for both).

And DMA_DATA_DONE does come. jz_mmc_irq() clears the flags of masked
interrupts, DMA_DATA_DONE among them, and on the X1600 writing that bit
also clears DATA_TRAN_DONE and DMAEND, which most likely is why reads
looked unfinished.

So the X1600 needs no driver change here, only dmas in its device tree
like the other Ingenic SoCs.

Sorry for the noise,
Olivier