[Letux-kernel] Raspi3B+ support in Letux Kernel

H. Nikolaus Schaller hns at goldelico.com
Wed Jan 9 10:21:47 CET 2019


Hi,

> Am 08.01.2019 um 21:59 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> Hi all,
> 
> With that I now get a __symbols__ section in the DTB. But there
> is no __overrides__. Strange, how that is generated from the github
> tree. Maybe it is explicitly in some .dtsi there?

I have now done a couple of additional tests (on Udoo neo with SD card reader):

First test:

	dtc -s -I dtb -O dts /media/letux/boot/bcm2710-rpi-3-b-plus.dtb >bcm2710.dts
	dtc -s -I dts -O dtb bcm2710.dts >/media/letux/boot/bcm2710-rpi-3-b-plus.dtb
	dtc -s -I dtb -O dts /media/letux/boot/bcm2710-rpi-3-b-plus.dtb >bcm2710-2.dts
	diff bcm2710.dts bcm2710-2.dts
	-> no diffs

This shows that the non-kernel dtc does not loose any information.

And: this dtb boots!

Next test:

	vi bcm2710.dts
		remove the __overrides__ section
	dtc -s -I dts -O dtb bcm2710.dts >/media/letux/boot/bcm2710-rpi-3-b-plus.dtb

This dtb still boots which means the __overrides__ section is not important.

3rd test:

	vi bcm2710.dts
		remove the __symbols__ section
	dtc -s -I dts -O dtb bcm2710.dts >/media/letux/boot/bcm2710-rpi-3-b-plus.dtb

Now ... this also boots!

Which means that a missing -@ is not the problem...

So it must be a detail in the upstream dts sources itself. Maybe a missing pinmux for the UART?
Or a differently set clock or power supply? Or the swapped uart numbers/names/aliases.

I still wonder how the upstream developers of Raspi patches do boot on their devices...

BR,
Nikolaus



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