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

Keith Packard keithp at keithp.com
Tue May 29 23:17:59 PDT 2007

On Wed, 2007-05-30 at 15:05 +1000, Drew Parsons wrote:

> If I plug in the external monitor (and run xrandr --auto), then the
> video displays on VGA while showing the blue window on LVDS at the same
> time. From what you wrote I understand this is the behaviour you
> intended.

Yes, the overlay can only be displayed on one crtc; it's a hardware
limitation. You can modify the crtc to be used when both display the
image by manipulating the XV_PIPE property. No, I don't know what tool
does this.

> The problem occurs if I then unplug the external monitor (and run xrandr
> --auto).  In this case, even though only LVDS is now used, it still
> displays the blue window instead of video. 

Can you send the output of xrandr --verbose after unplugging the
external monitor? Does the server correctly detect that the monitor has
been disconnected? And did you stop/restart the playback application?

It's supposed to detect on a frame-by-frame basis which crtc it should
use, but I'm not sure I tested that as completely as I could have.

keith.packard at intel.com
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