LCD screen flickering with kernel 2.6.28 / 2.6.29 patched

I’m was able to get kernel 2.6.28 and 2.6.29 with appropriate patches using http://www.rcn-ee.com/deb/kernel/beagle/jaunty/ but I have one little problem with both kernel with my LCD monitor. I’ve even tried with the already compiled kernels like the ones found at http://www.rcn-ee.com/deb/kernel/CC-beagle-v2.6.29-58cf2f1-oer31.1 but I believe it’s all the same.

The problems isn’t serious but mostly annoying. My LCD screen will flicker on and off (loosing signal) randomly a couple of times and the it will be OK for another 15 sec or so and then it will start another round of flickering. It’s not a fast flicker but actually a slow one. The signal will be lost and regained in a matter of 3 seconds for my monitor anyway. My monitor is a Dell UltraSharp 2709W. I’ve tried both hdmi to hdmi and hdmi to dvi but I that didn’t help.

I remember at one point when I was testing with the different kernels I did successfully get 2.6.29 or later running on the beagle board without flickering but the patches to fully support the rest like usb ehci was not present. So this leads me to believe that it’s a kernel issue and that the fix is out there somewhere just not part of the current active patches that I’ve tried.

Would anyone be able to help me with this problem?

Thanks everyone,
Miguel

Hi Miguel,

DSS2 development is still ongoing, for some 2.6.29 is miles ahead of
2.6.28 in correctly detecting/outputting to lcd's. However there
still are some corner cases...

It's not up yet, but could you give 2.6.29-*-oer34 a try? It has some
more updated DSS2 patches.

When uploaded, (it's building) it'll be located here:
http://www.rcn-ee.com/deb/kernel/beagle/jaunty/v2.6.29-58cf2f1-oer34/

Install directions are on the elinux wiki...

Regards,

Hey Robert,

Thanks for the response. I’ll try oer34 tonight, it should probably be up by that time.
I’ll keep you posted on the results.

Thanks,
Miguel

I’ve used the uImage from oer34 and I still have the same flicker. I’ve seen also the two kernel modules there? Do I need to copy those to my environment?

omaplfb.ko
pvrsrvkm.ko

I guess I’ll have to poke around with the LCD stuff. I’ve noticed that if I build 2.6.29-omap1 without any patches I don’t get the LCD flicker but USB isn’t working If add the patches then I lose stable LCD and gain USB support. :frowning:

On a side note regarding those kernel module I mentioned above, I haven’t tried copying those because I’ve just realized that now my root filesystem isn’t synced with my kernel version because I’m now building modules for 2.6.29 and the root file system as been setup for 2.6.28-omap1 using OE.

What would be the best solution to solve this problem. I was thinking of getting OE to build another root filesystem but this time with 2.6.29 as default kernel but I’m not sure how to do that yet. OE is defaulting to 2.6.28-omap1 when I build console-image

Any ideas?

Hi Miguel

I've used the uImage from oer34 and I still have the same flicker. I've
seen also the two kernel modules there? Do I need to copy those to my
environment?

omaplfb.ko
pvrsrvkm.ko

Nope for a default install, you don't need them.. Only if you want to
'play' around with sgx acceleration they are useful, but lets get your
screen working first..

Darn, well, does dmesg show anything useful as far as the lcd
information? What resolution setting are you attempting to set?

I'm not sure which one is needed by add these to your bootargs:

omapfb.debug=y omapdss.debug=y

Enable both to be on the safe side. You might also need to log over
the serial port, since dmesg doesn't always catch the intial
boot/setup..

I guess I'll have to poke around with the LCD stuff. I've noticed that if I
build 2.6.29-omap1 without any patches I don't get the LCD flicker but USB
isn't working If add the patches then I lose stable LCD and gain USB
support. :frowning:

Note: The lcd patches are separated into the dss directory...

USB in the musb directory...

On a side note regarding those kernel module I mentioned above, I haven't
tried copying those because I've just realized that now my root filesystem
isn't synced with my kernel version because I'm now building modules for
2.6.29 and the root file system as been setup for 2.6.28-omap1 using OE.

What would be the best solution to solve this problem. I was thinking of
getting OE to build another root filesystem but this time with 2.6.29 as
default kernel but I'm not sure how to do that yet. OE is defaulting to
2.6.28-omap1 when I build console-image

Any ideas?

The Angstrom stable/2009 defaults to 2.6.28, where as the dev branch
has 2.6.29. The lcd/usb stuff is builtin the kernel so it shouldn't
be effected by userspace. (and that uImage would only look in
/lib/modules/2.6.29-oer34/)

Regards,

Hi Miguel

I've used the uImage from oer34 and I still have the same flicker. I've
seen also the two kernel modules there? Do I need to copy those to my
environment?

omaplfb.ko
pvrsrvkm.ko

Nope for a default install, you don't need them.. Only if you want to
'play' around with sgx acceleration they are useful, but lets get your
screen working first..

Darn, well, does dmesg show anything useful as far as the lcd
information? What resolution setting are you attempting to set?

I'm not sure which one is needed by add these to your bootargs:

omapfb.debug=y omapdss.debug=y

Enable both to be on the safe side. You might also need to log over
the serial port, since dmesg doesn't always catch the intial
boot/setup..

I guess I'll have to poke around with the LCD stuff. I've noticed that if I
build 2.6.29-omap1 without any patches I don't get the LCD flicker but USB
isn't working If add the patches then I lose stable LCD and gain USB
support. :frowning:

Note: The lcd patches are separated into the dss directory...

USB in the musb directory...

On a side note regarding those kernel module I mentioned above, I haven't
tried copying those because I've just realized that now my root filesystem
isn't synced with my kernel version because I'm now building modules for
2.6.29 and the root file system as been setup for 2.6.28-omap1 using OE.

What would be the best solution to solve this problem. I was thinking of
getting OE to build another root filesystem but this time with 2.6.29 as
default kernel but I'm not sure how to do that yet. OE is defaulting to
2.6.28-omap1 when I build console-image

Any ideas?

The Angstrom stable/2009 defaults to 2.6.28, where as the dev branch
has 2.6.29. The lcd/usb stuff is builtin the kernel so it shouldn't
be effected by userspace. (and that uImage would only look in
/lib/modules/2.6.29-oer34/)

Regards,

Hey Robert,

I had a feeling that those 2 modules weren’t needed, thx for clearing that up.

I’ve added those 2 flags to my u-boot bootargs and here’s the output I got.

Seems by default that it's trying to initialize my screen with 640 x 480.

Seems like dmesg was able to log the omapdss and omapfb output but is there
any info explaining how I could of gotten the log working through serial?

Thx for explaining modules with OE. I guess you're right I don't really
need to worry about this for now.

Miguel

Hi Miguel,

I believe 640x480 is the default resolution. (so the pico projector
works out of the box)

Looking at the specs of your lcd, give this a try in the bootargs:
"omapfb.mode=dvi:1280x720MR-16@60"

For serial output, "console=ttyS2,115200n8" should dump everything...

Regards,

Hey Robert,

Great I’ll give that a try.

I had try another similar line for the bootargs but it had not worked. I wasn’t aware these had changed in 2.6.29.
Good to know. I really hope this works. I feel like I’m dragging you on this one.

Thanks,
Miguel

Bingo!!

The new line for the omapfb did the trick. No more flicker and in the end I get a way better resolution than the default one.

Thanks a lot for your help.

Miguel