i945GM don't show video at vga port (blue screen)

[Wang Zhenyu]

On 2007.05.31 15:25:09 +0000, Drew Parsons wrote:
> On Wed, 2007-05-30 at 08:25 -0600, Keith Packard wrote:
> > On Wed, 2007-05-30 at 18:05 +1000, Drew Parsons wrote:
> > 
> > >       "XV_PIPE" (range 0 to 1)
> > >               client settable attribute
> > >               client gettable attribute (current value is -1)
> > 
> > Oops. I didn't fix the range; perhaps your client is resetting this
> > value, which would break things. I'm using the new value '-1' to
> > indicate that the driver should choose the pipe automatically.
> > 
> 
> I used xvattr to change XV_PIPE to 0 and to 1, but it didn't make any
> difference to the video displayed on LVDS, it still came up blue.
> 
> With both LVDS and VGA displaying at the same time, VGA got the correct
> video with XV_PIPE set to either 0 or 1.
> 

Yes, it looks like in i830_crtc_dpms_video() after we stop video, overlayOK is 
false, and later if we want to turn video on, it will fail in 
	if (crtc != pPriv->current_crtc)
	    return;
as current pipe is changed. So overlayOK will never be turned true. 

I'm not sure how to fix this, didn't go through all the code yet.