BBB HDMI jitter issue

You mentioned that this was seen in 3.8.11, and I saw something similar in 3.8.11 prior to applying this patch:

https://github.com/RobertCNelson/linux-dev/blob/am33x-v3.8/patches/hdmi/0005-Enable-output-of-correct-AVI-Infoframe-type-hdmi.patch

The issue that I saw was the “sync” being lost when using an HDMI display (both audio and video). In my experimenting, just using 3.8.11 without the patch resulting in intermittent signal loss: http://www.youtube.com/watch?v=JZEn6VOoGuc

As I disabled various aspects of the signal (shut off audio, HCDP, etc.) the signal became more “stable” with less flickering. In one case, the screen was skewed to the right a little bit and jittered a little bit without audio. The reason for this was because the AVI infoframes were being sent with a different format (the format at the time of HDMI subsystem initialization) versus the current format. This is probably the issue that was fixed for Robert.

Gerald is correct that the 3.8.x kernel tree is the Wild West right now. Patches are being worked on every day.

Great input!

Honestly. I don’t really know which direction the 3.8 kernel is going. Jason Kridner handles the SW. Right now, he isn’t saying much. I don’t know how many of these patches are being picked up, ignored, or just not aware of their existence.

Gerald

Hi and thank you for your infos…

at the moment I found a good option installing
Angstrom-Cloud9-IDE-GNOME-eglibc-ipk-v2012.12-beaglebone-2013.04.13.img.xz on SD
or BBB-eMMC-flasher-2013.04.13-DDR3-400MHz-ID.img.xz on MMC

hoping there will be a fix asap :slight_smile:

thanx fo support
Maurice

Hi Andrew,

could you please post a link where to download a recently built kernel with this patch?
and/or could give me some info on building the kernel with this patch?

thank you very much,
Maurice

I always build my own kernels using Robert Nelson’s github repository, so I don’t know what prebuilt one to recommend. Take a look at http://www.eewiki.net/display/linuxonarm/BeagleBone+Black in the “Linux Kernel” section for information on how to build the kernel that I use. All of the patches that are in the git repository are patched against the source tree prior to building. To review all of the patches that will be included, take a look at https://github.com/RobertCNelson/linux-dev/tree/am33x-v3.8/patches . The patches under the “hdmi” subdirectory will be of interest to you. The patch that I mentioned (that fixes the AVI infoframes) is the 0005 patch. Robert is very good about keeping the patches up to date as they roll into Angstrom, so you can build your own kernel with whatever patch fixes there are without having to wait until a formal Angstrom release is made. With the rapid pace of development for the BBB, I find it worth the extra effort to watch for patches and build my own kernel to incorporate fixes ASAP, rather than wait for a prebuilt one to become available.

Hi Andrew,
thank you very much for the links…
I will try to follow this line :slight_smile:

Maurice