[U-Boot] rockchip: rk3399: set fdtfile

[Mark Kettenis <mark.kettenis@xs4all.nl>]

> From: klaus.goger at theobroma-systems.com
> Date: Mon, 19 Mar 2018 08:17:49 +0100
> 
> > On 17.03.2018, at 09:48, Mark Kettenis <kettenis@openbsd.org> wrote:
> > 
> > Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
> > Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
> > ---
> > include/configs/rk3399_common.h | 1 +
> > 1 file changed, 1 insertion(+)
> > 
> > diff --git a/include/configs/rk3399_common.h b/include/configs/rk3399_common.h
> > index d700bf2549..9a5de3a7e3 100644
> > --- a/include/configs/rk3399_common.h
> > +++ b/include/configs/rk3399_common.h
> > @@ -59,6 +59,7 @@
> > #include <config_distro_bootcmd.h>
> > #define CONFIG_EXTRA_ENV_SETTINGS \
> > 	ENV_MEM_LAYOUT_SETTINGS \
> > +	"fdtfile=rockchip/" CONFIG_DEFAULT_DEVICE_TREE ".dtb\0" \
> > 	"partitions=" PARTS_DEFAULT \
> > 	BOOTENV
> > 
> 
> This assumes that the devicetree files in U-Boot and the OS are the
> same.  As it's our goal to keep Linux devicetrees in sync
> with U-Boot this patch should be fine in the long-term. But at the
> moment this only applies for rk3399-firefly (on Linux).

Hi Klaus,

As far as I understand things loading the "final" device tree passed
to the OS (or EFI bootloader) from disk is more or less a generic
"distro" boot feature.  The device trees don't really need to be the
same.  As long as the final device tree has the right hooks for U-Boot
to pass along things like Ethernet MAC addresses and framebuffer setup
things should just work.  This feature allows the device tree to be
updated without recompiling U-Boot to include a new device tree.

I use this feature quite extensively on other boards to use the latest
Linux mainline kernel device trees that often include additional
devices or important fixes.  I suppose on Linux systems GRUB has
support for loading a new device tree.  But in that case any changes
made by U-Boot will be lost.

> Mark, where would one find the devicetrees included in OpenBSD?
> I looked in sys/arch/amd64 but couldn'tfind any.

As Jonathan already indicated, we use the Linux device trees on
OpenBSD.

> Anyhow, I'm fine with that change.

Great!

> Tested-by: Klaus Goger <klaus.goger@theobroma-systems.com>

Thanks!