[U-Boot] [PATCH] jetson-tk1: Set fdtfile environment variable

Alexander Graf
2016-04-15T21:15:02Z

On 14.04.16 00:29, Tom Rini wrote:
> On Wed, Apr 13, 2016 at 07:42:11PM +0200, Andreas F?rber wrote:
> [snip]
>> $fdtfile needs to be the Linux filename. It does not always follow the
>> same pattern as the U-Boot variables you suggest here.
>> CONFIG_DEFAULT_DEVICE_TREE ".dtb" might work better, and that was my
>> question to you.
>>
>> It's part of the generic mechanism, so not just select boards. Yet I was
>> told that all boards are expected to set their cacheline size (although
>> that is not a board but CPU property), so similarly we can (yes, newly)
>> desire all boards to provide DT related settings as well.
>>
>> If you would supply a feature-complete DT in the first place, we
>> wouldn't need $fdtfile here, but it seemed that that was not realistic
>> to expect for the upcoming U-Boot release.
>
> So here's the thing. Figuring out what the device tree to load is, and
> where it's going to reside is a sucky problem. For most of the complex
> cases we do this today with "run findfdt". Why? Well, check out the
> implementations in "git grep -l findfdt=" right now. It sounds like we
> need to figure out how to get EFI in line with everything else that
> U-Boot does/supports rather than to re-invent the wheel here.

Sure, I fully agree. Where exactly do you see the EFI bits
reimplementing the wheel here? We use the same logic as the rest of
U-Boot for this. Findfdt gets called before the distro boot command, so
we use that. If a board sets fdtfile, we use that. If it doesn't, with
v2 we fall back to the same logic as pxe boot for fdtfile naming fallbacks.

So in the end, I'd say it's pretty much in line :).

Alex