Re: [PATCH 3/4] ARM: tegra: nyan-big: Include compatible revisions for proper detection

[Jon Hunter <jonathanh@nvidia.com>]

On 21/09/16 08:43, Paul Kocialkowski wrote:

...

>>>>>>> Depthcharge (the payload used with cros devices) will attempt to
>>>>>>> detect
>>>>>>> boards using their revision. This includes all the known revisions
>>>>>>> for
>>>>>>> the nyan-big board so that the dtb can be selected preferably.
>>>>>>
>>>>>> May be I am missing something here, but for the mainline there is only
>>>>>> one dtb available and so why is this needed for the mainline?
>>>>>
>>>>> There is indeed a single dts in mainline, but depthcharge will use the
>>>>> revision
>>>>> to match the compatible string (e.g. it will look for google,nyan-big-
>>>>> rev5,
>>>>> not
>>>>> google,nyan-big), so we need to list them all in that single dts.
>>>>> Otherwise,
>>>>> depthcharge will fall back to the default config, which may or may not
>>>>> be
>>>>> suitable for nyan.
>>>>
>>>> Is tegra124-nyan-big.dtb not the default?
>>>
>>> You can't expect that to always be the case. The image format allows many
>>> different dts to be provided, so I could easily build with
>>> multi_v7_defconfig
>>> and have various dts for various devices in the same image, and just select
>>> a
>>> random one as default.
>>
>> Really? Sounds odd. I was hoping that tegra124-nyan-big.dtb would be a
>> catch all.

I meant I was hoping that compatible = "google,nyan-big" would be the
catchall not the dtb file name ;-)

> Yes, the image format (FIT) allows specifying multiple dtb and zImage
> combinations in the same image[0].

Yes I am aware of that. Typically, I have been testing using a FIT image
with single zImage and dtb. Hence no problems.

So are you wanting to create a FIT image to support multiple boards and
use the single FIT image for all? If so then I can see why you want
this. Again please describe the motivation for the changes in the
changelog so it is clear why we are adding this.

Cheers
Jon

-- 
nvpublic