Re: [RFC/PATCH] lib/Kconfig: Enable OF_LIBFDT_OVERLAY by default when FIT is enabled

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tom,

On Fri, Mar 10, 2023 at 01:12:24PM -0500, Tom Rini wrote:
> On Sun, Jan 29, 2023 at 06:30:22PM +0200, Laurent Pinchart wrote:
> 
> > FIT image support is commonly used to bundle a kernel image, a device
> > tree, and device tree overlays. Applying overlays requires the
> > OF_LIBFDT_OVERLAY config option to be set, which lots of boards fail to
> > select, most likely because developers never noticed. This leads to an
> > error when trying to apply overlays:
> > 
> > "config with overlays but CONFIG_OF_LIBFDT_OVERLAY not set"
> > 
> > TI ARM boards select the option by default. Extend this to all systems
> > that select the FIT option. This only affects the default, overlay
> > support can still be disabled manually in the configuration.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > Reviewed-by: Marek Vasut <marex@denx.de>
> > Reviewed-by: Simon Glass <sjg@chromium.org>
> > ---
> > I'm posting this as an RFC to get feedback. If the idea is generally
> > appreciated, I'll update the defconfig files accordingly.
> 
> Alright, so, I put this through a world build, and most platforms grow
> by 4-5kB.

Thank you for testing this, despite the patch falling off my radar.

> I think that means what I'd really like to see as a starting
> point is more SoCs doing an "imply OF_LIBFDT_OVERLAY if OF_LIBFDT && FIT"
> or adding to the default y list below, or similar.  If that brings us to
> the point where a good number of ARM boards with FIT are enabling it, we
> can default y if ARM, for example.  But right now it's more like several
> hundred boards growing in size, which is uncomfortable, given the size
> it's growing by.

I'm fine with that.

I've submitted the original patch because I had to update a
vendor-supplied U-Boot binary to get overlay support, which ended up
being a bit rabbit hole for various reasons. I thought it would be nice
to save users from this kind of trouble. I can send patches to enable
the option for SoC I care about, but generally speaking, who should
decide which SoC(s) should imply OF_LIBFDT_OVERLAY ?

-- 
Regards,

Laurent Pinchart