[Intel-gfx] source-based replacement for video bios on ivybridge -- I'm stuck!

[Daniel Vetter]

On Wed, Aug 01, 2012 at 06:47:58PM -0700, ron minnich wrote:
> Dear intel graphics experts:
> 
> I am looking at trying to get coreboot to move away from binary video
> bios on google chromebook platforms. The current target is an
> ivybridge system. We'd like to get minimal graphics going with a
> source-based startup code in coreboot, such that we can avoid the
> issues that come with binary video bioses.
> 
> The good news is that the kernel driver works fine without a video
> bios having been run -- the new samsung chromebox/chromebook work in
> this manner.
> 
> As an experiment, I have used cocinnelle to extract the relevant
> driver functions from the kernel (in this case 3.4.2) and am running
> them in user mode. I've had good luck with prototyping hardware
> drivers for coreboot in user mode, and this approach is *almost*
> working on this graphics hardware.
> 
> You can see the result here: http://pastebin.com/3e77Y66C
> 
> The I2C is working, and I'm recovering EDID and the mode. I can
> control the panel backlight. I can easily program the GTT and other
> simple functions.

Sounds rather awesome ;-)

> The issue now is that I am not able to get the link trained. I figure
> I'm misordering or missing some crucial step, and on the off chance
> that some one of you can look at that output and say "Ron you idiot!
> You're missing *this* step" I've posted it.
> 
> If anyone has any thoughts on this I'd welcome them. This thing is
> close, and I feel it is possible, but I've obviously got something
> wrong.
> 
> Thanks in advance for any help or advice you can give me!

DP link training is a feeble beast, and we've fixed quite a few issues
just recently. I suggest you retry with the drm/i915 code from 3.6-rc1, in
particular the following two patches:

commit 0d71068835e2610576d369d6d4cbf90e0f802a71
Author: Paulo Zanoni <paulo.r.zanoni at intel.com>
Date:   Fri Jun 29 16:03:34 2012 -0300

    drm/i915: try to train DP even harder

commit 2514bc510d0c3aadcc5204056bb440fa36845147
Author: Jesse Barnes <jbarnes at virtuousgeek.org>
Date:   Thu Jun 21 15:13:50 2012 -0700

    drm/i915: prefer wide & slow to fast & narrow in DP configs

Cheers, Daniel

[Note that not all these fixes are cc: stable, since we fear that they
might blow up on onther configurations - these things always need tons of
testing.]
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48