[U-Boot] [PATCH 2/3] video: add support for display controller in MB86R0x SoCs

[Matthias Weißer]

Am 28.04.2010 08:44, schrieb Wolfgang Denk:
> Dear Matthias,

>
> in message<4BD7D5DD.6080701 at arcor.de>  you wrote:
>>
>>>> +	pGD->memSize = VIDEO_MEM_SIZE;
>>>> +	pGD->frameAdrs = PHYS_SDRAM + PHYS_SDRAM_SIZE - VIDEO_MEM_SIZE;
>>>
>>> Please pay attention to the global memory map requirements. PRAM might
>>> go first.
>>
>> Can you please explain this a bit more in detail? I checked the source
>> and README for CONFIG_PRAM and it seems to be reserving some space at
>> the end of RAM. But I have only found reference to it in ppc and m68k code.
>
> Right. But there is a chance that the ARM implementation might be
> reworked soon, and then it will follow the documented approach as
> well, so better start correctly from the beginning so you don;t run
> into conflicts soon.

I totally agree with you, but...

>> What would be the correct way to reserve some 2MB-4MB at the end of
>> system RAM as a framebuffer for the integrated graphics device?
>
> See the PPC implementation for reference.

I had a look into the PPC code and its clear to me how it is done there. 
But I currently do not see how this can be done on ARM without a couple 
of changes to arch/arm/lib/board.c

Another question regarding the video driver:
I have seen some video drivers in driver/video/... and some are in 
arch/.../cpu/...

What would be the right place for mine? As it is integrated into the SoC 
I tend to put it in arch/arm/cpu/arm/arm926ejs/mb86r0x and not into 
drivers/video. On the other hand there is a imx31 related video driver 
in drivers/video.

Thanks for you patience
Matthias