Quoting Rob Herring (2024-01-15 12:32:30)
> On Fri, Jan 12, 2024 at 12:07:47PM -0800, Stephen Boyd wrote:
> > diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
> > index da9826accb1b..9628e48baa15 100644
> > --- a/drivers/of/Kconfig
> > +++ b/drivers/of/Kconfig
> > @@ -54,9 +54,14 @@ config OF_FLATTREE
> > select CRC32
> >
> > config OF_EARLY_FLATTREE
> > - bool
> > + bool "Functions for accessing Flat Devicetree (FDT) early in boot"
>
> I think we could instead just get rid of this kconfig option. Or
> always enable with CONFIG_OF (except on Sparc). The only cost of
> enabling it is init section functions which get freed anyways.
Getting rid of it is a more massive change. It can be the default and
kept hidden instead? If it can't be selected on Sparc then it should be
hidden there anyway.
>
> > select DMA_DECLARE_COHERENT if HAS_DMA && HAS_IOMEM
> > select OF_FLATTREE
> > + help
> > + Normally selected by platforms that process an FDT that has been
> > + passed to the kernel by the bootloader. If the bootloader does not
> > + pass an FDT to the kernel and you need an empty devicetree that
> > + contains only a root node to exist, then say Y here.
> >
> > config OF_PROMTREE
> > bool
[...]
> > @@ -195,6 +191,17 @@ static inline int of_node_check_flag(const struct device_node *n, unsigned long
> > return test_bit(flag, &n->_flags);
> > }
> >
> > +/**
> > + * of_have_populated_dt() - Has DT been populated by bootloader
> > + *
> > + * Return: True if a DTB has been populated by the bootloader and it isn't the
> > + * empty builtin one. False otherwise.
> > + */
> > +static inline bool of_have_populated_dt(void)
> > +{
> > + return of_root != NULL && !of_node_check_flag(of_root, OF_EMPTY_ROOT);
>
> Just a side comment, but I think many/all callers of this function could
> just be removed.
>
> I don't love new flags. Another possible way to handle this would be
> checking for "compatible" being present in the root node. I guess this
> is fine as-is for now at least.
Ok. I can add a check for a compatible property. That's probably better
anyway. Should there be a compatible property there to signal that this
DT isn't compatible with anything? I worry about DT overlays injecting a
compatible string into the root node, but maybe that is already
prevented.
