FreeBSD on Utilite (revisited)

[Oleksandr Tymoshenko]

> On Feb 28, 2016, at 11:18 PM, Martin Waschbüsch <martin at waschbuesch.de> wrote:
> 
> 
>> Am 29.02.2016 um 07:29 schrieb Russell Haley <russ.haley at gmail.com>:
>> 
>> It seems compulab's imx6 som is called the CM-FX6. There are some imx6-cm-fx6 and imx6q-cm-fx6 files in their linux kernel on github?
>> 
>> ‎https://github.com/utilite-computer/linux-kernel/tree/utilite/devel/arch/arm/boot/dts
> 
> Thank you, Russ.
> 
> There already is a dts file for the cm-fx6 in the FreeBSD kernel sources
> for instance /usr/src/sys/gnu/dts/arm/imx6q-cm-fx6.dts
> 
> However, the same is true for the Wandboard
> /usr/src/sys/gnu/dts/arm/imx6qdl-wandboard.dtsi
> and yet, Crochet uses the files found under
> /usr/src/sys/boot/fdt/dts/arm/

In early days of FDT support number of supported ARM boards was really
small and people tended to write their own DTS files from the scratch,
instead of using ones from Linux due to licensing concerns. These
DTS files were placed to boot/dts/fdt. As number of supported hardware
grew it became clear that this practice is a dead end, we can't keep
up with changes provided by vendors. So after some research it was
concluded that we can bring DTS files from Linux. I don't remember
exact reasoning but the gist of it: they're not code, they're set 
of facts about hardware. "Upstream" files were placed to gnu/dts.

Some of the files in boot/dts/fdt are just wrappers around
vendor-provided dts/dtsi files, fixing Linux-specific 
idiosyncrasies or adding new nodes. for instances, there
is no PRUSS node in Linux DTS for beaglebone, but 
boot/fdt/dts/arm/beaglebone-common.dtsi adds it.

You should be able to use .dts file in either directory, build system
checks boot/fdt first and then gnu/ AFAIR. 

> 
> So, I went with the wandboard-quad.dts file from there, seeing as it should be quite similar to my Utilite Pro.
> So far, no luck. Once the loader slurps in the compiled .dtb, the system hangs with no further sign of activity.


Check stdout/stderr settings in “chosen” node. Looks like
imx6q-cm-fx6.dts uses UART4 for serial output while Wandboard 
quad uses UART0.