hdmi output not detected by xrandr

[sashan]

On Sat Nov 26 22:13:49 2011, Keith Packard wrote:
> On Sun, 27 Nov 2011 16:01:52 +1100, sashan <sashan at zenskg.net> wrote:
> > Hi
> > 
> > I'm trying to figure out why the external hdmi output on my laptop doesn't work
> > but am not sure where the problem is or if this is the right mailing
> > list.
> 
> I'd bet money that the hdmi connector is only hooked up to the nVidia
> device, which means you'd have to use that one to display anything over
> that connector.
> 

Yeah that might be the case but the document
http://www.nvidia.com/object/LO_optimus_whitepapers.html about nvidia optimus
basically says that the datapath to the physical monitor is always through the
Intel IGP and then the IGP is responsible for writing to the display. The
nVidia chip is between the application and the IGP, therefore I expected that
the IGP would be connected to the HDMI port. However I'm probably wrong and
would appreciate if you or someone could clarify my understanding about how this
is meant to work.

The laptop is a Dell XPS 15z
(http://reviews.cnet.com/laptops/dell-xps-15z/4507-3121_7-34714594.html)