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

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 11/09/2015 07:36 AM, Thierry Reding wrote:
> 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

That's not currently a supported use-case.

> , in which case nvtboot
> would still need to be responsible for setting this up.

I assume s/nvtboot/whatever other bootloader is in use/?

> 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?

The L4T U-Boot source code:-)