[okl4-developer] gta01 and framebufer

[Remy Gottschalk]

Hi Geoffrey,

Thank you for your reply.

On Tue, 2008-05-20 at 02:02 +1000, Geoffrey Lee wrote: 
> On Mon, May 19, 2008 at 05:37:59PM +0000, Remy Gottschalk wrote:
> > Hi all,
> > 
> 
> Hi Remy
> 
> 
> > I am trying to get some display under wombat with gta01 as target. If i
> > understood well I have two options : using the Linux native drivers or
> > the iguana native drivers plus a stub in Linux.
> > 
> > For the first solution I found out that the drivers to be used is the
> > s3c2410 lcd driver (ie : s3c2410fb). But it depends on ARCH_S3C2410 and
> > thus don't seems to be directly usable.
> > So i tried to add this arch and enable it with scary results (as
> > expected).
> > I also tried to forcefully enable the drivers without adding the arch by
> > tricking the dependencies. It gives better results and the only thing
> > left to compile correctly is that  dma_alloc_writecombine and
> > dma_free_writecombine are missing.
> > I suppose that it is due to dma not being fully available in wombat.
> > 
> > So for this option the questions are :
> > Is s3c2410fb indeed the correct drivers to use ?
> 
> 
> Yes, I believe so. 
> 
> > Should it be feasible to make the drivers work without the full arch
> > support ?
> 
> Yes, I believe so.  You will need to somehow pull in the all the
> dependencies of the driver though.  As you have noticed, some of the
> functions that this driver depends on are missing.
> 
> > If I interpreted correctly the problem, how could I replace the missing
> > functions ?
> 
> You will need to reimplement in arch/l4 and include/asm-l4.  how they
> are implemented will depend on exactly what function you are trying
> to re-implement.  In some cases you can base it on a loose equivalent on
> the one for the native port, in some cases you may have to rely on using
> Iguana / L4 APIs.
> 
> > 	
> > For the second option. It seems that with the default configuration the
> > right iguana native lcd drivers is already activated and running. 
> > I assumed that wombat's iguana virtual framebuffer is the corresponding
> > stub and started to work with it. It seems that the wombat drivers is
> > still designed to use the old drivers framework while the iguana's
> > drivers is implemented with the v2 framework.
> > So I tried to make the wombat stub evolve (using the serial drivers as
> > reference) and I am stuck pretty soon since iguana_getenv("VLCD_TID");
> > return NULL. 
> > 
> > So for this option :
> > Are my assumptions correct ? (Is iguana's drivers using v2 and wombat's
> > one expecting v1 ?)
> > Are VLCD_TID and VLCD_HNDLE supposed to exists or do they need to be
> > created ?
> > If it needs to be created, how ?
> 
> I took a quick look and it appears that the vLCD has been
> temporarily disabled in the devicecore.  Have a look at
> platform/s3c2410/iguana/devicecore/src/device_core.c.  I
> 

It seems that this file is not used anymore, in fact it appear that none
of platform/*/iguana/devicecore/src/device_core.c are compiled anymore.
I only tested for pc99 and gta01 arch though.

However I managed to get the whole thing to work. I am now able to play
video using mplayer from wombat with iguana's lcd drivers and wombat
framebuffer stub. (victory !).

I will soon post the whole procedure I followed probably as an howto
since it may interest some people.

-- 
Remy Gottschalk - rgottschalk at linagora.com
Ingénieur informatique embarquée
Groupe LINAGORA - http://www.linagora.com
Tél.: +33(0)1 58 18 68 28 - Fax : +33(0)1 58 18 68 29