Hello!
I need to transfer a large amount of data from a device (around 8 Mbit/s)and PC
104 seems like the right choice. The transfers can be performed by directly
reading data, but I'd like to use DMA.
I dug through the drivers for sdcard and nand flash and I found the dma_op()
function which seems to do the magic. Unfortunately, so far it didn't work for
me. I don't get any reads on the PC 104 bus.
I tried writing the DMA controller registers directly, with no results. The
problem is that when I read the registers, the addresses apper to be
incremented and the control register is modified, so it should work...
So I am left with a few questions:
1. First of all, has anyone used DMA on PC 104? I couldn't find any information.
2. Is 0xE8000400 the right base address for the DMA controller?
3. Which of the 8 DRQ/DACK pairs should I use with my peripheral?
4. I programmed the DMA with the physical address 0xEE0003E8 for the
peripheral, and the result of the virt_to_phys() for the internal buffer. Am I
doing something wrong? (I read somewhere that DMA controllers use bus addresses
which can be different from physical addresses.)
Note 1: All DRQ lines but DRQ2 are at 3.3V, which seems a little strange to me.
Note 2: Looking as various schematics, I came across TS-7KV which apparently
uses DRQ3/DACK3. Unfortunately, I wasn't able to find the driver that uses dma
transfers with this peripheral.
Sorry for the long post... I hope someone can help me out.
Thank you!
Adrian Grigore
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