MPC85xx DMA support for Kernel 2.6?

[Kumar Gala]

On Jun 30, 2005, at 10:12 AM, Clemens Koller wrote:

> Hello!
>
> I am planning to use DMA/burst access for copying large chunks of data
> (100MBytes) from the Local Bus (UPM accessed SRAM) to System Memory  
> (DDR)
> as fast as possible (200MBytes/s). (As you can guess, that's a  
> framegrabber).
>
> As far as I have seen, the DMA engines of the MPC85xx (fsl-dma) are  
> not
> supported in the classical way (dma_request(), free_dma()) in the  
> kernel 2.6.x.
> The memory allocators in arch/ppc/dma-mapping.c seem to be usable,
> but there is no valuable dma support yet (true?).
>
> I can program the DMA Controllers in my MPC8540 on my own to  
> achieve what I want
> but it would be great to get/produce/stick with as much cross- 
> platform reusable
> code as possible.
>
> Is there any ongoing work to put DMA support for the mpc85xx and  
> similar
> devices into the kernel? Is there any ongoing work in this area
> or is somebody working with the fsl-dma and can publish some code and
> share some ideas?

I'm not aware of anyone work on such a thing.  I'd be more than happy  
to accept patches for it.  I know several of us have written some  
APIs on top of the DMA for 85xx.  Those however are non-standard APIs.

What APIs exist for general purpose DMA engines?  Last time I looked  
at this problem nothing really existed.

- kumar