[Buildroot] Beaglebone Black - Buildroot

Anders Darander anders at chargestorm.se
Mon Mar 30 05:03:34 UTC 2015

Hi Martin,

I'm adding the buildroot mailing list as CC, as the question is pretty
generic relating to buildroot and beaglebone.

* Martin Beaudet <martin.beaudet at intelia.com> [150329 00:30]:
> I'm trying to use Buildroot (Latest version) with the Beaglebone Black
> RevC. I need an image having a minimal footprint having (Qt5, nodejs,
> systemd, nano, some other packages).

Minimal... ;)

> As I'm planning using the Beaglebone with 4 similar projects, I think
> that Buildroot is a good candidate to help me in the
> automation/customization process of the output image.

Sure, buildroot should be a good candidate

> I successfully build an image but I'm not getting HDMI output.  By the
> way, I did try with the stock image and the HDMI is working on my LG
> 22'' and a also on my cape 7'', so it is not a hardware failure.

I've never tried the HDMI output myself, so I can't really comment on

> I notice that you have made some patch to Buildroot so it is why I'm
> wondering if you can help me. Have you done something similar with
> good result ?

> Here is how I done it:

> $ make beaglebone_defconfig
> $ make menuconfig

> I add some missing package (ti-gfx, glibc, etc...) and I build the
> image using :

> $ make

> I then prepared the MicroSDCard :

> $ sudo mount /dev/sdf1 /media/boot
> $ sudo mount /dev/sdf2 /media/rootfs
> $ sudo cp MLO u-boot.img zImage uEnv.txt *.dtb /media/boot
> $ sudo dd if=rootfs.ext2 of=/dev/sdf2
> $ sudo umount /dev/sdf1
> $ sudo umount /dev/sdf2

> I insert the MicrosSDCard into the BeagleBone, hold the S2 button down
> and then wait until the beaglebone boot. Notice that I have an HDMI LG
> 24'' monitor connected to the beaglebone and also the console (FTDI)
> to my Windows computer (putty).

> The monitor remain always blank, the beaglebone do not output on the

Have you added any application / configuration that actually should
output anything on the HDMI output?

The buildroot image is per default (unless it has changed recently,
which I doubt) headless only and serial console only. If the FB is
configured and started is something I've never checked myself.

> Someone on buildroot give me a patch to allow tilcdc to be selected in
> the kernel. I applied this patch. (Patch of
> tilcdc<http://repo.or.cz/w/buildroot-gz.git/patch/6312b9a5c5e37708042c0b24df8928ab74007ef9>).

This probably should be enough.

Though, please, double check that the configurations mentioned in
actually are enabled and that the tda998x module is present and loaded.
Also double check the comment regarding the DTS.

> I rebuild the kernel :

> $ make linix-dirclean
> $ make kernel
> $ make

> Copy the new kernel (zImage) to the SDCard. But the same problem, no
> hdmi output.

> While looking to the dmesg, I notice this error :

> [    1.402202] tilcdc 4830e000.lcdc: no encoders/connectors found
> [    1.408337] tilcdc 4830e000.lcdc: failed to initialize mode setting

These errors are what prompts me to direct you to the email above.

> I also tried modifying the uEnv.txt and setting additional video
> parameters found on internet but same blank screen.

> I asked some help on the Beaglebone community but they simply tell me
> to not reinvent the wheel and use this procedure :
> https://eewiki.net/display/linuxonarm/BeagleBone+Black. This is
> interesting but I'm losing the ability to automate and customize (per
> project) my building image process.

I couldn't open that link, though I suspect they're directing you to use
Ubuntu or Debian based images... I'd agree with you, that that's not the
way to go for an embedded project.

> Then I begin to wonder if it would not be the ti-kernel repo point in
> BuildRoot that is too old ?

> BR2_LINUX_KERNEL_CUSTOM_REPO_URL="git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git"
> BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="7f280334068b7c875ade51f8f3921ab311f0c824"

> This repo seem to be pointer on the 3.12 kernel. Maybe the problem is
> here ? Bad DTS or bad kernel configuration.... If I simply update this
> rep version to a 3.14, do I have any chance that it works without any
> other Buildroot modification ?

Ouch, I actually thought I had updated it to a 3.14 based kernel...
Though, according to the email I linked to above, it should work on 3.12

I'd try to find some time to update to the lastes head from the
ti-linux-3.14.y branch of ti-linux-kernel.git. (This is the repo used in
the official TI BSP's).

> Or maybe change it to :

> BR2_LINUX_KERNEL_CUSTOM_REPO_URL="https://github.com/RobertCNelson/bb-kernel.git"

Personally, I've not used that repo at all, so I can't vouch for it.

> Or could it be a too old U-Boot ?

This shouldn't really matter.


-- They finally got King Midas, I hear.  Gild by association.
Anders Darander
ChargeStorm AB / eStorm 

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