[Mageia-dev] Mageia support for GMA 3600 (Cedar Trail Atom)

[tux99-mga at uridium.org]

On Sun, 11 Mar 2012 tux99-mga at uridium.org wrote:
>
> On Fri, 9 Mar 2012 tux99-mga at uridium.org wrote:
> 
> > On Fri, 9 Mar 2012, Thomas Backlund wrote:
> > 
> > > tux99-mga at uridium.org skrev 8.3.2012 02:18:
> > > >
> > > > Hi,
> > > > I just tried Mageia 2 beta 1 on a Intel DN2800MT board hoping that it
> > > > would have framebuffer support for the GMA 3600, but the attached
> > > > monitor goes into standby (no signal) as soon as the frame buffer gets
> > > > activated during boot.
> > > >
> > > > As far as I understand there is frame buffer support in the 3.3 kernel
> > > > for the GMA 3600 so in theory it should work.
> > > >
> > > > Are you aware of this issue or should I do a bug report?
> > > 
> > > Yes.
> > > 
> > > There is a bug with Cedar Trail that got fixed upstream a few days after
> > > 3.3-rc6 was released, so the fix is not in our current 
> > > kernel-3.3.0-0.rc6.1.mga2, but it will be fixed in the next build.
> > 
> > Thanks, that's great, I will test the next build and then report back 
> > how that works with my Cedar Trail board.
> 
> Hi, I noticed a new kernel packages showed up in the cauldron repo 
> (3.3rc7) so I tried it immediately (reinstalled cauldron from scratch as 
> I had overwritten the previous install with other distro tests) using 
> the boot.iso image, but the video behaviour at boot is still the same, 
> the monitor still goes into no-signal standby as soon as the drm stuff 
> is started.

Just for future reference for anyone who might come across this thread 
in the ML archives facing the same issue:

I solved this, the GMA 3600 kernel DRM driver in 3.3.0 (as included in 
Mageia) always assumes a LVDS panel is present (as would be the case 
on netbooks but not on mini-ITX boards) and for some reason it defaults 
to a 1920x1080 panel.
To avoid this and therefore to be able to use the other video outputs 
(VGA, hdmi) at other resolutions the following kernel parameter needs to 
be appended on the grub kernel line:

video=LVDS-1:d

This will force disable the LVDS port and with that parameter Mageia 2 
works fine on a Cedarview Atom DN2800MT board.

This is a shortcoming of the kernel module (not specific to Mageia), 
Alan Cox is aware of it and I guess it will eventually be fixed.

For anyone interested the xorg.conf I used is here (the monitor 
section is specific to my monitor, hence will need adapting):
http://pastebin.com/X7mpEF3x

Also for anyone interested I have done some power draw measurements of 
the Intel DN2800MT Cedarview Atom board comparing Mageia 2 beta with 
some other distros (and Win 7), the results are here:

http://www.linuxtech.net/reviews/intel_DN2800MT_cedarview_atom_power_draw.html