[PATCH] scripts/Makefile.lib: also consider $(CONFIG_SYS_BOARD)-u-boot.dtsi

[Tom Rini]

On Mon, Oct 02, 2023 at 09:39:18AM -0600, Simon Glass wrote:
> Hi Tom,
> 
> On Mon, 2 Oct 2023 at 09:12, Tom Rini <trini at konsulko.com> wrote:
> >
> > On Mon, Oct 02, 2023 at 08:43:41AM -0600, Simon Glass wrote:
> > > Hi Tom,
> > >
> > > On Mon, 2 Oct 2023 at 08:09, Tom Rini <trini at konsulko.com> wrote:
> > > >
> > > > On Sun, Oct 01, 2023 at 07:17:27PM -0600, Simon Glass wrote:
> > > > > Hi Tom,
> > > > >
> > > > > On Fri, 29 Sept 2023 at 10:02, Tom Rini <trini at konsulko.com> wrote:
> > > > > >
> > > > > > On Fri, Sep 29, 2023 at 09:15:00AM -0600, Simon Glass wrote:
> > > > > > > Hi Rasmus,
> > > > > > >
> > > > > > > On Mon, 25 Sept 2023 at 13:05, Rasmus Villemoes
> > > > > > > <rasmus.villemoes at prevas.dk> wrote:
> > > > > > > >
> > > > > > > > On 25/09/2023 20.19, Tom Rini wrote:
> > > > > > > > > On Mon, Sep 25, 2023 at 10:27:43AM +0200, Rasmus Villemoes wrote:
> > > > > > > > >> On 04/05/2023 14.35, Rasmus Villemoes wrote:
> > > > > > > > >>> On 03/05/2023 16.54, Tom Rini wrote:
> > > > > > > > >>
> > > > > > > > >>>> The one last problem now is on stm32mp15_dhcor_basic which is a
> > > > > > > > >>>> defconfig missing one from OF_LIST but including it in the its file, so
> > > > > > > > >>>> the above is the patch we need.
> > > > > > > > >>>>
> > > > > > > > >>
> > > > > > > > >> Hi Tom
> > > > > > > > >>
> > > > > > > > >> Can I persuade you to try something like
> > > > > > > > >> https://source.denx.de/u-boot/u-boot/-/commit/a05e0d0e6b9103542a1076f9cab0005f400fa072
> > > > > > > > >> again, but leaving the .dtbo targets in there?
> > > > > > > > >>
> > > > > > > > >> I could send a patch, but it's entirely mechanical, and not really meant
> > > > > > > > >> for being applied until we know if there's more to be cleaned up.
> > > > > > > > >
> > > > > > > > > So what ended up being the problem I think is the case Simon pointed out
> > > > > > > > > where we do take the output from "make all" and concatenate one of the
> > > > > > > > > dtbs that was generated with u-boot.img or so, and it works.  But maybe
> > > > > > > > > that should just list all of the valid DTBs that it needs in the
> > > > > > > > > defconfig to start with? I don't quite know, it was a case I hadn't
> > > > > > > > > considered at the time.
> > > > > > > > >
> > > > > > > >
> > > > > > > > Re-reading the thread, I can't see where that was mentioned.
> > > > > > > >
> > > > > > > > But yes, if some boards (still) need that, and have more than one
> > > > > > > > possible .dtb, the board can't set an OF_LIST different from the default
> > > > > > > > consisting of DEFAULT_DEVICE_TREE because changing OF_LIST requires
> > > > > > > > SPL_LOAD_FIT || MULTI_DTB_FIT.
> > > > > > > >
> > > > > > > > How do we figure out if such boards even exist?
> > > > > > >
> > > > > > > Honestly at this point I've forgotten what this is all about.
> > > > > > >
> > > > > > > Perhaps the easiest approach is to create a new Kconfig to control
> > > > > > > whether a board-level .dtsi is included in the list of wildcard
> > > > > > > searches. Then you can enable it for your board without affecting
> > > > > > > others.
> > > > > >
> > > > > > That's getting things backwards, from what this cleanup does.  Today we
> > > > > > have messy lists of "build these device trees" and then don't use most
> > > > > > of them, and some of the list is just Wrong (listing dts files as an
> > > > > > output).  With the series to handle dtbo files, we could remove
> > > > > > virtually all of that, and the only use cases that don't Just Work still
> > > > > > are the ones I forget which board you mentioned (I think it was Samsung
> > > > > > tho?) where the defconfig doesn't list all of the device trees, just one
> > > > > > of them, and the other 5 that we build can also be easily used.  Does
> > > > > > that ring a bell?
> > > > >
> > > > > Yes it does...but what is the problem here?
> > > >
> > > > Messy and unused and incorrect Makefile content.
> > >
> > > The problem I see there is people using TARGET in
> > > arch/arm/dts/Makefile for example. There are 80 instances of that. The
> > > rules should depend on SoC (e.g. use ARCH_EXYNOS5), as Linux does it.
> >
> > It shouldn't be there at all since there's almost no cases where we
> > "just" take an arbitrary dtb file and u-boot.img and then the system
> > boot.  That's what this series is about fixing.
> 
> I'm really not sure that replacing build rules with a board CONFIG is
> a good idea. I suppose part of my confusion is why the Makefile is
> considered a problem?

Because it's duplicative and as Rasmus points out, often wrong.

> > > > > The DT files for an SoC are supposed to be buildable without needing
> > > > > to have the context of a particular board.
> > > >
> > > > They're still buildable, without an explicit rule, they just need to
> > > > (like they can now) be built explicitly.
> > >
> > > But isn't that creating dead code? It will rot.
> >
> > No, that's the problem we have today, people list something in the
> > Makefile, since they think they need to list something, and then put the
> > device trees they use in the defconfig.
> 
> If they don't list something, it won't build, right?

No, everyone builds fine since CONFIG_DEFAULT_DEVICE_TREE is pretty much
always set.  And for run time, if we need more, *OF_LIST gets set.

> > [snip]
> > > > > I am find with making the boards list the DTs that they can run with,
> > > > > if there is an easy way of doing that. CONFIG_SPL_OF_LIST is just for
> > > > > SPL, I think.
> > > >
> > > > Yes, every board except for some use case you've described before as far
> > > > as I know lists the device trees that they use in the defconfig.  Which
> > > > is why there's an impetus to clean up arch/*/dts/Makefile as 95% of
> > > > those lines can just be removed.
> > >
> > > It seems like you are wanting a board-level CONFIG which lists the DTs
> > > which need to be built for that board. Is that right? You are
> > > suggesting that this already exists, but I am not aware of it. Do you
> > > mean SPL_OF_LIST, perhaps?
> >
> > I mean today CONFIG_DEFAULT_DEVICE_TREE + CONFIG_OF_LIST +
> > CONFIG_SPL_OF_LIST is set and correct for everyone board except some use
> > case you have, which I think is something about exynos?  And so we only
> > need scripts/Makefile.dts in arch/*/dts/Makefile
> 
> Yes exynos5 boards (the original reason for DT) have / had the same
> u-boot-nodtb.bin and you can add the DT you want to boot it on
> particular hardware. That is one of the goals of DT.

Yes, but "and you concat the two files" isn't common.  We _can_ keep the
EXYNOS list, if that's actually being used.  But most of that list is
not, as far as I can tell, because the flow is "U-Boot binarie(s) + DTB
files + stuff" to get the correctly formatted blob for the firmware.

> The OF_LIST option is a little vague but I think it means that the DTs
> are packaged into a FIT in u-boot.img - is that right? But they
> presumably have to be built first.

No, they don't have to be built first because scripts/Makefile.dts
ensures that we build everything in *OF_LIST.

-- 
Tom
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 659 bytes
Desc: not available
URL: <https://lists.denx.de/pipermail/u-boot/attachments/20231002/b2e35473/attachment.sig>