Re: ppc85xx DMA

[Naru Sundar <nsundar@fulcrummicro.com>]

Ah hah.  I got it working. 

Turns out using the ioremapped address was bad, I had to use the actual
nonremapped physical address.

Thanks for the info!

-naru

On Tue, Jun 06, 2006 at 02:16:10PM -0700, Naru Sundar wrote:
> To clarify, I am definitely using the physical addresses.  virt_to_bus and
> virt_to_phys result in the same value.  My transfer completes and I see
> BCR go back to 0, but I can't manage to actually see any data difference
> at the destination side.
> 
> The destination address is an ioremapped region that I pass through
> virt_to_phys.  The src is kmalloc'd memory that has GFP_DMA set.
> 
> On Tue, Jun 06, 2006 at 11:55:48AM -0700, Naru Sundar wrote:
> > On Tue, Jun 06, 2006 at 09:39:29AM +0800, Liu Dave-r63238 wrote:
> > > What is the DMA transfer mode? Is direct or chaining mode?
> > 
> > Direct mode.  I fixed an error with my bit ordering for the configuration
> > registers, and now the transfer seems to complete, but I don't see any
> > actual data showing up in the destination register that I am writing to.
> > 
> > > Did you ioremap the DMA register space?
> > 
> > Yes, I can write the destination address manually.  So I am thinking my addresses
> > are wrong.
> > 
> > For the source and dest address I used:
> > 
> > dma_map_single(NULL, ptr, len, DMA_TO_DEVICE)
> > 
> > (which effectively does a virt_to_bus on ppc and so should just return to me
> > the bus address used by the dma).
> > 
> > -naru
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