On Tue, May 12, 2020 at 6:32 AM Luca <[email protected]> wrote:
>
> [Edited Message Follows]
> [Reason: Simplify issue description and fix link]
>
> Hi all,
>
> in general I am interested in using a dts to get a dtbo and get the second 
> one loaded by u-boot when using SOC AM335x (my current test board is a 
> Beagleboard green).
> At the moment I am trying to use a BB-BONE-LCD5-01-00A1.dts to customise the 
> kernel device tree.
>
> Unfortunately, despite setting the "overlay_files" variable in uEnv.txt:
>
> the generated BB-BONE-LCD5-01-00A1.dtb on the boot folder of the MMC seems to 
> have no effect.
> I don't see any useful info on the u-boot log.
> checking on /sys/firmware/devicetree/base I am not able to tell if the dtbo 
> has been loaded
>
>
> I am using:
>
> meta-ti: branch zeus, commit 1dd4558 (with a fixed .wks see 
> https://lists.yoctoproject.org/g/meta-ti/message/12916). I will probably 
> switch to tag ti2020.00 or previous if needed
> poky: branch zeus, commit ca9cc50
> meta-openembedded: branch zeus, commit 44e458f
> MACHINE set to beaglebone
>
> Notes
>
> BB-BONE-LCD5-01-00A1.dtbo has been generated by a recipe that uses the 
> devicetree.bbclass (See device-tree.bb and openembedded-core).
> to get the .dtbo in the boot partition when using WIC the local.conf (or 
> <machine>.conf or ...) has been edited adding the followiing line
>
> IMAGE_BOOT_FILES_append = " devicetree/*"
>
> Doubts:
>
> taking a look to the u-boot tag ti2020.01.00 used by the meta-ti version I am 
> using, I see that CONFIG_OF_LIBFDT_OVERLAY is not set for am335x. Therefore I 
> suppose that the variable overlay_files set in uEnv.txt would have no effect 
> for am335X SOC, is it correct?
> If the previous point is correct, which is the suggested approach to 
> customise the device-tree with current u-boot? Probably using the "single FIT 
> image" described in overlay-fdt-boot.txt in i-boot sources?
>
> Any suggestion would be much appreciated.

Just use the BeagleBone "Green" base dtb, use the "fdtoverlay" dtc
utilty to add the BB-BONE-LCD5-01-00A1 on top of the Green *.dtb and
load it like normal in yocto..

Regards,

-- 
Robert Nelson
https://rcn-ee.com/
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