800x480 Display broken on i.MX25 with MMU

[Sascha Hauer]

On Wed, Apr 18, 2012 at 12:41:39AM +0200, Eric Bénard wrote:
> Hi,
> 
> on an i.MX25, it seems that 3100ea14668853aeedae85ec83e3536b59ba7728
> broke framebuffer usage with a 800x480 display when MMU is enabled :
> about 1/4 of the display (at the bottom) is garbage.
> 
> v2011.08.0 : it works fine
> 
> v2011.09.0 : it fails
> 
> disabling MMU makes it work again in v2011.09.0
> 
> then in v2011.09.0 it works with MMU enabled after reverting the
> following commits :
> 43ebdba64a6e1c12fe58aa57e905cfdcef922126
> 56c379160b9f0b52efcaaefce9adb6121d5865d7
> a6c333c7f2dbe49189dd5343da3c921659e88cbf
> 3100ea14668853aeedae85ec83e3536b59ba7728
> 
> So it seems something was broken during MMU rework and I don't yet know
> what : Sascha do you have an idea ?

What is the address of your framebuffer memory? The LCDC has a nasty
limitation, the DMA controller can only access 4MB, the other address
lines are fix. This means that you can't cross a 4MB boundary with the
framebuffer. Currently this case is not caught anywhere.

Sascha


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