Minimal device tree for new board

[imrehg]

I have a Freescale i.MX6Quad based board, the VIA VAB-820, but it does not have upstream kernel support yet. I've seen that a lot of other i.MX devices are in the latest arm-soc kernel, and would like to add this board too. Its BSP is based on the SabreLite kernel from Freescale with this patch applied. I think most of the patch is just housekeeping and the board itself is very similar to the original SabreLite hardware. Using the SabreLite device tree (.dts) unfortunately I couldn't boot: the machine just hangs after "Uncompressing kernel" stage.

I was wondering what would be the absolute minimal device tree that a SabreLite board would boot with? The only thing I really need at this stage is probably the CPU, memory, and the debug UART output. If that works, everything else can be added step by step. So far I had no luck when trying backwards from imx6dl-sabrelite.dts and its dependencies.

[fabio_estevam]

Make sure you use a recent U-boot that allows booting dtb. U-boot 2009.08 from FSL does not have this support, so better use a current U-boot.

You should not use a imx6dl dts as reference. Use imx6q-sabrelite.dtb instead if your board is quad core.

Make sure your bootloader is calling  'bootz ${loadaddr} - ${fdt_addr}'

[imrehg]

Hi Fabio,

Indeed, the board reports a version string of U-Boot 2009.08 (Nov 11 2013 - 14:40:47), that can be a problem then... The board has a a patch for the u-boot as well, I've uploaded it here: https://gist.github.com/imrehg/24987ca8094e307dcd69 So I'd need to port this to a newer u-boot version to be able to boot with device tree attached to the kernel?

The imx6dl is my bad, the reference I actually meant was imx6q-sabrelite indeed.

For current testing I'm using buildroot and the following sequence in u-boot:

mmc dev 0

ext2load mmc 0 12000000 uImage

ext2load mmc 0 13000000 rootfs.cpio.uboot

bootm 12000000 13000000