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

[Paul Kocialkowski <contact@paulk.fr>]

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Resending with the right CC chain.

Le mercredi 21 septembre 2016 à 10:15 +0100, Jon Hunter a écrit :
> 
> 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 ;-)

Yeah, I figured :)

> 
> > 
> > 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.

Fair enough, will do in v2.

-- 
Paul Kocialkowski, developer of low-level free software for embedded devices

Website: https://www.paulk.fr/
Coding blog: https://code.paulk.fr/
Git repositories: https://git.paulk.fr/ https://git.code.paulk.fr/

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