[Intel-gfx] [PATCH] Use enable bit for LVDS detect

[Jesse Barnes]

On Friday, November 21, 2008 7:27 am Robert Noland wrote:
> On Fri, 2008-11-21 at 01:36 -0800, Keith Packard wrote:
> > On Fri, 2008-11-21 at 10:36 +0800, Zhenyu Wang wrote:
> > > This looks like a promising right way to check if LVDS
> > > is available or not. Because if LVDS is enabled on the board,
> > > it will be used as primary display, so video bios should already
> > > have initialized it.
> >
> > we've considered this in the past, but rejected it as a laptop which has
> > the lid closed or which is booted with a CRT connected will have the
> > LVDS disabled when the X server starts.
>
> FWIW, this is not the behavior that I see on my Dell D630.  LVDS is
> always enabled (GM965).  In order to use 2 external displays, I have to
> use xrandr to turn off LVDS and then enable VGA.  TMDS-1 is always
> mapped to pipe a.

another option would be to use Zhenyu's code in the i830_lvds.c detect 
function.  That way chips with LVDS builtin would still show an available LVDS 
output, but it wouldn't be detected as "connected" at xrandr & startup time.  
We should also use the lid switch for detection, so the detect function would 
look like:
  if ((I915_READ(LVDS) & LVDS_EN) && i830_lvds_lid_open(pI830))
    return TRUE;
  return FALSE;


-- 
Jesse Barnes, Intel Open Source Technology Center