[okl4-developer] framebuffer console inside okl4 and neo1973

[Nelson Tam]

Hi Dennis,

On 24/01/2008, at 11:37 PM, Dennis Gessner wrote:

> Back to my framebuffer-problem: Should the framebuffer-console work
> inside wombat? Maybe the iguana-framebuffer-driver needs some  
> changes to
> handle the framebuffer-console-input correctly?? Your last mail  
> sounded
> like it has to work without doing great changes.


Ok I've had a further look at this part of your question.

First of all, the L4 kernel part of console will not appear on the  
framebuffer.
You'll have to wait until OKLinux starts spitting data out on the  
console.

The Iguana framebuffer driver in release 1.5.2 doesn't do anything  
fancy besides
exposing the hardware framebuffer device to user-level code.   
Typically, you
can control parameters such as where the fb is in physical memory,  
what the RGB
encoding is, etc.

One thing to note here is that when gta01 boots, the bootloader (u- 
boot) also
initialises the fb in a proper and well-known state.  That explains  
why you can
always see a nice OpenMoko splash screen on startup.

Therefore, in order to get just a working framebuffer, you don't  
actually need
to do anything through the Iguana fb driver (because it's already done  
for you).
All you need to do is know where the fb is and write to the correct  
addresses in
memory.

Here at OKL, we've experimented with writing to the default fb region  
(as set by
u-boot), and also changing the fb to somewhere else in memory and  
writing to the
new fb region.  We've seen the correct changes on the LCD screen, so  
we have
confirmed that the Iguana fb driver is indeed working.

In any case, we've done funky demonstrations such as running Doom on  
OKLinux on
the OpenMoko phone, with the output on the LCD screen, so we know the  
framebuffer
works on OKLinux too :)

Therefore I'm fairly confident that there should be no technical  
reason why you
cannot get OKLinux to spit its console output onto the framebuffer.  I  
believe
the missing configuration is on the Linux side.

Have you enabled the 'fbcon' module in the Linux kernel config?

Sorry about the long rant, hope this helps.

--
(nt)

Nelson Tam
nelson at ok-labs.com