Re: [PATCH] drm/i915: VGA needs to be on pipe A on i830M

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Oct 23, 2012 at 10:49:23AM +0100, Chris Wilson wrote:
> On Sun, 21 Oct 2012 23:26:29 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> > The bit doesn't stick, and the output is always cloned from pipe A,
> > even when it's supposed to scan out from pipe B.
> > 
> > Shuts up annoying warnings from the modeset-rework, too.
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=51265
> > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> Tbh this doesn't surprise me that much, it wasn't until 855gm that
> attaching a second display and using an extended desktop became a
> selling point. I haven't spotted any such limitations form the docs yet,
> but xxtensive error reporting ftw,
> 
> Acked-by: Chris Wilson <chris@chris-wilson.co.uk>

I've noticed that with this patch we know get and unknown connection state
since the code can't find a suitable pipe for load detection. But that
beats the previous state of affairs, where it tried to use pipe B,
actually used pipe A and concluded that something is connected (although
it's the LVDS on pipe A and nothing on the VGA connector on pipe B).

I've tried to make load detect work by remapping the pipe->planes stuff,
so that crtc 0 will use pipe B and hence we still have something left for
load-detect on pipe A. But alas, that upset the hw a bit.

So there's still some things to figure out, but this here will at least
paper over some of the problems.

I'll add these more recent observations to the commit.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch