[U-Boot] U-Boot Sunxi breaks LCD output on Olimex Lime A10

[Hendrik]

I have always been using the sunxi u-boot from 
'https://github.com/linux-sunxi/u-boot-sunxi' and that works fine, but 
now I want to boot the kernel from USB. That is not possible in that 
u-boot branch. Therefore I switched to the latest U-Boot 
'git://git.denx.de/u-boot.git' for the Olimex Allwinner A10 Lime as this 
one does have a working USB mass storage implementation.

But when the kernel and root filesystem is booted and my application 
(using DirectFB) starts, the LCD screen is flickering between a correct 
image and an incorrect image as if sometimes random image data is 
displayed to the screen. Although it looks more like a clock or timing 
issue because the colors of the faulty screen resemble the colors of the 
correct screen. Also: when the cpu is inactive the screen is more or 
less ok but when doing a lot of work the screen starts to flicker. Then 
it is stable for a while and after some time it starts flickering again.

I am using the exact same kernel, root filesystem, U-boot environment, 
SD-card and 'script.bin' (which defines the hardware layout, I am not 
using a device tree file). The only difference is the version (and 
origin) of U-boot.

Can anybody shine some light on this? Maybe Hans de Goede? I have seen 
his name pop-up a lot of times with the Sunxi branch.

Regards,
Hendrik