[Intel-gfx] Broken LVDS output at mode changes

[Takashi Iwai]

At Thu, 29 Mar 2012 09:57:41 -0700,
Keith Packard wrote:
> 
> <#part sign=pgpmime>
> On Thu, 29 Mar 2012 18:12:56 +0200, Takashi Iwai <tiwai at suse.de> wrote:
> 
> > The strange thing is that, although you can recover the display by
> > turning off LVDS and on again once when the problem happens, but then
> > the display starts flickering.  And, the flickering continues even
> > after reboot on BIOS boot screen.
> 
> Yeah, it's clearly the panel which is confused. It would be nice to know
> what happened to the LVDS signal which caused this problem with the
> panel.

I'll try to poke someone in HP.

> > BTW, now I tested to disable LVDS unconditionally on different
> > platforms as Daniel suggested.  All worked fine, and I saw no
> > regressions.  Tested on IVY, SNB, ILK, GM45 and PineView.
> 
> That's not surprising -- pre-PCH platforms disabled the LVDS
> anyways.
> 
> I wonder if we could fix this by being more careful about the order of
> register operations during LVDS mode setting...

Sure, that'd be a preferred option.
If you have any easy test in mind, let me know.


thanks,

Takashi