[Nouveau] NVAC "No Signal"

[Lukas Wunner]

On Thu, Oct 20, 2016 at 10:08:28AM +0200, Lukas Wunner wrote:
> On Wed, Oct 19, 2016 at 07:58:06PM +0200, Pierre Moreau wrote:
> > For example, my laptop (which also has an NVAC) has been triggering the
> > no-signal message on external monitors way before Ben???s patch landed,
> > but only for some adapters. I haven???t tried Ben???s patch yet, nor
> > yours, but I will certainly do it, and see what effect each of them has.
> 
> The external DP port on your MBP5,3 is switchable between GPUs and
> the apple-gmux driver switches it in unison with the panel.  Thus
> the NVAC cannot drive external displays when gmux is switched to
> the MCP79.  (You probably were aware of this, just wanted to mention
      ^^^^^
I meant G96, sorry I mixed it up.

Lukas

> it in case you weren't.)  (In theory we could change vga_switcheroo
> and apple-gmux to support switching the panel and the external port
> separately rather than in unison if there is demand.  It's only
> supported on MBPs introduced from 2008 to 2010 though, the 2011+
> models can only drive external ports with the discrete GPU.)