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

[Hans de Goede]

Hi,

On 10/01/2014 07:43 PM, Hendrik wrote:
> 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.

Hmm, the only thing I can think of which may have caused this are the
recent DRAM controller code cleanups which are in upstream u-boot and
not in https://github.com/linux-sunxi/u-boot-sunxi

Can you try copying these 2 files:

arch/arm/cpu/armv7/sunxi/dram.c
arch/arm/include/asm/arch-sunxi/dram.h

>From https://github.com/linux-sunxi/u-boot-sunxi over into upstream
u-boot, essentially reverting the DRAM cleanup patches, and see if that
fixes things ?

Regards,

Hans