[PATCH] drm/etnaviv: move GPU linear window to end of DMA window

[Lucas Stach]

Am Mittwoch, den 09.03.2016, 12:25 +0000 schrieb Russell King - ARM
Linux:
> On Mon, Feb 29, 2016 at 05:20:16PM +0100, Lucas Stach wrote:
> > If the end of the system DMA window is farther away from the start of
> > physical RAM than the size of the GPU linear window, move the linear
> > window so that it ends at the same address than the system DMA window.
> > 
> > This allows to map command buffer from CMA, which is likely to reside
> > at the end of the system DMA window, while also overlapping as much
> > RAM as possible, in order to optimize regular buffer mappings through
> > the linear window.
> 
> I've been pondering this for a while now, and I think we should not
> do this unconditionally - it should be predicated on the MC20 feature -
> both for the original code and the new code.  If we don't have the MC20
> feature, we end up with more memory spaces than we can cope with.
> 
> If we don't have MC20, but we need to offset, that's an error which
> can lead to memory corruption.
> 
This makes sense.

I guess not using the offset on MC10 will also allow you to enable TS on
those parts? In that case we might advertise this with a patchlevel
change of the API.

Regards,
Lucas