[U-Boot] [PATCH v2 5/7] Tegra30: Cardhu: Add DT files

Stephen Warren
2012-12-04T00:57:37Z

On 12/03/2012 05:49 PM, Simon Glass wrote:
> Hi Stephen,
>
> On Mon, Dec 3, 2012 at 4:40 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> On 12/03/2012 04:45 PM, Tom Warren wrote:
>>> These are stripped down for bringup, They'll be filled out later
>>> to match-up with the kernel DT contents, and/or as devices are
>>> brought up (mmc, usb, spi, etc.).
>>>
>>> Signed-off-by: Tom Warren <twarren@nvidia.com>
>>
>>> diff --git a/arch/arm/dts/tegra30.dtsi b/arch/arm/dts/tegra30.dtsi
>>
>>> +/ {
>>> + model = "NVIDIA Tegra30";
>>
>> We don't really need a model property here, but it's not a big deal.
>
> We do actually use it in U-Boot (in ARM patches on the mailing list).

Hmmm. The tegra20.dtsi file doesn't have one...

>>> diff --git a/board/nvidia/dts/tegra30-cardhu.dts b/board/nvidia/dts/tegra30-cardhu.dts
>>
>>> +/memreserve/ 0x1c000000 0x04000000;
>>
>> /memreserve/ isn't correct for U-Boot; no memory should be reserved.
>
> But don't we want to use the same fdt for U-Boot as the kernel?

The only reason for a memreserve are:

a) To reserve the current display frame-buffer. This is a run-time thing
that U-Boot should add to the DTB itself, not pre-populated in the DT.

b) To reserve memory for some kind of co-processor. We shouldn't be
using memreserve for this any more, but rather allocating the memory
dynamically in the kernel.

So irrespective of the answer to your question we should still remove this.

Re: your question: Perhaps, but we're so far away from that right now,
it almost doesn't seem worth caring yet. Also, while we should certainly
use the same bindings, I'm not sure we should use the same actual .dtb
file bitstream, since the .dtb passed to the kernel should be loaded
from the filesystem/... where the kernel zImage was, not embedded into
the bootloader.