RFC: Support for U-Boot phases in Kconfig

[Tom Rini]

On Wed, Aug 11, 2021 at 08:03:00AM -0600, Simon Glass wrote:
> Hi Tom,
> 
> On Wed, 11 Aug 2021 at 07:47, Tom Rini <trini at konsulko.com> wrote:
> >
> > On Wed, Aug 11, 2021 at 06:56:31AM -0600, Simon Glass wrote:
> > > Hi Tom,
> > >
> > > On Tue, 10 Aug 2021 at 13:38, Tom Rini <trini at konsulko.com> wrote:
> > [snip]
> > > > I need to take another pass at converting a bunch of symbols, to see
> > > > where we're at.  Probably the biggest chunk of progress next would be to
> > > > start converting CONFIG_SYS_xxx to SYS_xxx and moving defines out of
> > > > config.h and in to something else.  I'm taking a peek at some of the
> > > > remaining PCI ones now.
> > >
> > > How about we set a deadline for this? It has gone on for too long and
> > > we just need to drop these CONFIGs. It's probably a higher priority
> > > than a Kconfig change.
> > >
> > > I was expecting that the config.h files would go away and we would use
> > > Kconfig (or DT) for everything. What sort of things don't fit into
> > > that model?
> >
> > Environment is the hard one to move out from config.h and in to, well, I
> 
> Well you know my views on that :-)
> 
> http://patchwork.ozlabs.org/project/uboot/patch/1382763695-2849-4-git-send-email-sjg@chromium.org/
> 
> I still think it makes more sense than #defines and I can resurrect
> that series if you like.

That might work, yeah.  I just also want to focus on less things in
progress at once.  That too I think has been part of why everything is
taking so long.

> > don't know what.  I think there's also a handful of symbols like
> > CONFIG_SPL_MAX_SIZE that are a little tricky to convert directly (they
> > do math based on other symbols) rather than just as evaluate-and-set.
> 
> We can either evaluate them and put the answer in as the defconfig
> value...or perhaps ask Masahiro to support evaluation in kconfig?!

I do forget what kind of operations are allowed in Kconfig at this
point, it might be possible now, yes.  And if not, something worth
trying.

> > Right now, a little more than half of the unmigrated symbols are
> > CONFIG_SYS_xxx things and those likely should become SYS_xxx things.  Of
> > the ones that don't just go away.
> 
> Do you mean things like this?
> 
> arch/m68k/include/asm/immap.h:#define CONFIG_SYS_PCI_BAR0
>  (0x40000000)
> 
> Assuming this doesn't move to devicetree, it should be in its own asm/
> or asm/arch header file I think, not in the config.h file at all.
> 
> FSL layerscape should move CONFIG_SYS_PCIE3_PHYS_SIZE et al to devcetree.

I started and set aside *PCI* since a bunch of that goes away once
UCP1020 gets updated.  But yes, there are lots of CONFIG_SYS_xxx things
that live inside and outside of config.h and step one is likely a simple
regex.  They aren't really configurable.  We can try and figure out what
"get this from DT" approach makes sense after.

> Some of the DM migrations will help - e.g. for I2C. NAND seems to have
> a lot - who is the NAND maintainer?

There's not currently a NAND maintainer.

> But really what I am asking is, can we set a deadline where all
> config.h files will be dropped? It has been 7 years...

It's going to come down once again to figuring out what to do about
older platforms.  Since I picked on khadas platforms earlier, here's
where meson64.h looks really good.  All of the platforms use
include/configs/meson64.h and that's very little outside of environment
stuff.  To go back to another part of the thread, it also shows how hard
environment stuff is.

It also reminded me that buildman never got kconfiglib support directly
and we still have genboardcfg.py to spit out boards.cfg to be parsed by
buildman.

-- 
Tom
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