[U-Boot] [PATCH 4/4] ARM: tegra210: gpu: configure WPR region

[Thierry Reding]

On Wed, Oct 28, 2015 at 11:59:04AM -0600, Stephen Warren wrote:
> On 10/18/2015 10:57 PM, Alexandre Courbot wrote:
> >T210's GPU secure firmware loading requires a write-protected region
> >to be set up.
> >
> >This patch reserves the upper 256KB of RAM as the WPR region and locks
> >it so the kernel can initiate secure firmware loading.
> 
> On T210, it's the responsibility of nvtboot (which runs before U-Boot) to
> set up any and all carve-outs. This code should not be necessary, and indeed
> I expect the registers it touches can't actually be programmed from U-Boot,
> which runs in non-secure mode after WPR is already locked.

Can we document this assumption somewhere? It's entirely possible that
someone might want to run U-Boot without nvtboot, in which case nvtboot
would still need to be responsible for setting this up. Or if it isn't
we could still point at some location where the interactions between a
first stage bootloader and U-Boot are documented.

Do we have a document of this kind already?

Thierry
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