[PATCH] arm64: tegra: Add the GPU on Tegra194

[Terje Bergstrom]

On 7/16/2020 6:17 AM, Thierry Reding wrote:
> On Thu, Jul 16, 2020 at 01:59:33PM +0100, Jon Hunter wrote:
>> I also see that for gv11b we populate 'dma-coherent' and so we should
>> probably add this as well.
> Do we know for certain that the GPU is DMA coherent? I've only tested
> this (with local patches to Nouveau) without dma-coherent, so I have not
> actually verified that it works without.
>
> I vaguely recall reading that there are different apertures for sysmem,
> one for coherent sysmem and another for non-coherent sysmem. So I'm not
> sure if dma-coherent here will work without additional code in the
> driver to ensure that all memory is allocated from the coherent sysmem
> aperture.

We do have the choices of coherent and non-coherent memory accesses in 
the iGPU via the two sysmem apertures. But in Tegra194 we're forcing 
coherency from the memory subsystem side, so all accesses are coherent.

Terje