[RFC 4/4] drm: Add NVIDIA Tegra support

[Arnd Bergmann]

On Thursday 12 April 2012, Marek Szyprowski wrote:
> Scatter lists were initially designed for the disk based block io operations, 
> hence the presence of the in-page offsets and lengths for each chunk. For 
> multimedia use cases providing an array of struct pages and asking dma-mapping 
> to map them into contiguous memory is probably all we need. I wonder if 
> introducing such new calls is a good idea. Anrd, what do think? It will 
> definitely simplify the drivers and improve the code understanding. On the 
> other hand it requires a significant amount of work in the dma-mapping 
> framework for all architectures, but that's not a big issue for me.

My feeling is that it's too much like the existing _sg version, so I wouldn't
add yet another variant. While having a simple page array is definitely
simpler and potentially faster, I think the API is already too complex
and we need to be very careful with new additions.

	Arnd