On 02/24/2010 02:52 PM, Tony Lindgren wrote:
* Philip Balister<philip@xxxxxxxxxxxx> [100224 14:28]:
On 02/24/2010 12:35 PM, Tony Lindgren wrote:
* Philip Balister<philip@xxxxxxxxxxxx> [100224 11:31]:
I am trying to setup a dma operation to copy memory from GPMC
address space into RAM. The only examples using the omap-dma api use
hardware triggers.
When I start a transfer, I end up with a DMA transaction error when
I start the transfer.
Does anyone have a good example of a software transfer? Currently, I
am tracing the omap dma api to see how things map into the registers
....
Enjoy the GPMC timings. I recommend attaching a logic analyzer there
to verify the things are right for the key lines if you have chance.
Hmm I thought the hardware triggers were optional in at least
drivers/usb/musb/tusb6010_omap.c.. Maybe I don't remember correctly.
GPMC is easy :)
Sounds like you just got lucky! :)
OK, I am using the 2K non-multiplexed mode atm :) Still I have a logic
analyzer and am confident I can get the mux'd modes working. Burst is
still a bit scary.
Basically, I have a device attached to a GPMC chip select and I need
to read/write to it. The GPNC bit is fine, we'd just like to use the
DMA controller to move the data.
That should work, at least there has been several memory-to-memory
dma test modules posted here over the years. Have you tried using
OMAP_DMA_NO_DEVICE for omap_request_dma? Also search for omap dmatest
or similar.
Thanks. This is suggesting I am on the right track, but the transfer
still fails with: DMA transaction error with device 0.
The call to omap_set_dma_transfer_params adds these two args:
params->trigger, params->src_or_dst_synch);
I think they are more for hw synched transfers and set them to zero.
the src|dest param setting calls added the params->src_ei,
params->src_fi arguments. I've set these to 1.
Any more clues?
Philip
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