On Tue, Oct 16, 2012 at 6:25 AM, Peter Robinson <pbrobinson(a)gmail.com> wrote:
> Made good progress today. :)
> Was able to get Device Tree to work on both Panda ES and Trimslice.
Awesome!
> What works: appended DTB kernels. (cat the .dtb to the end of the
> zimage, then generate a new uImage)
>
> What does NOT work: loading the .dtb from u-boot (similar to the initrd)
It's a good start.
> One notable breakthrough was being able to boot the trimslice with the
> latest version of u-boot.
> (had to change boot.cmd to have root=/dev/mmcblk0p3)
OK, interesting to see why labels don't work.
> For the panda it would seem not all the parts of omap kernel are moved
> over to DT, some things do not work.
Not surprised as I believe 3.7 should be the end of the OMAP DT
support additions but it's good to know it actually works which is my
primary concern so that we know it has all the bits needed in F-18.
Peter
A few things to discuss:
* update u-boot in f18 to 2012-10 (important for panda)
-> Apparently we only bundle u-boot with omap anyways.
-> The updated version only appears for f19, this would be a "nice to
have" type thing for f18.
-> Only the updated version loads the .dtb succesfully from u-boot,
otherwise we can append the .dtb in 2012-07.
* Do we even want to load the .dtb for panda?
-> my experience was not happy, the omap4-panda.dtb makes things break.
-> Breaks: WiFi, Display Subsystem and maybe USB-Host functionality.
-> I do believe the omap folks are busy working on improving DT, so
maybe we can wait?
* Trimslice
-> was able to get mmc/sdcard booting with the latest DT-enabled u-boot.
-> unfortunately when Brendan ran into a snag when reproducing with
his internal /dev/sda boot.
-> on the trimslice the .dtb seems to have to be appended, so far
loading via u-boot is not happy.
-> also there is a rumor that trimslice might support a uEnv.txt type
thing, would be nice to have.
* adding the .dtb's to the distro.
-> I hear the .dtb files are somehow generated from the kernel sources?
-> sometimes we may have to append them to the kernel zimage (trimslice).
-> Other times they get loaded via u-boot (Panda).
-> Would be interesting to findout how our image generation process
deals with this.
-> necessary first step is deciding how we get access to the .dtbs
from the distro.
--
-Jon