https://bugs.freedesktop.org/show_bug.cgi?id=39696
--- Comment #7 from Klaus Kusche klaus.kusche@computerix.info 2011-08-09 09:07:03 PDT --- (In reply to comment #6)
(In reply to comment #5)
Doesn't work the way we would like it:
- All outputs can be connected to all CRTC's.
- Default is LVDS:0, DP: 1
- Even if the mode is exactly the same: As soon as I connect the DP to CRTC 0
using xrandr, xrandr automatically reconnects LVDS to CRTC 1 (and if I reconnect the LVDS, DP is also switched). Hence, they can exchange CRTC's, but running both from the same CRTC seems to be impossible.
However, according to xrandr -- verbose they are not clones. How do I set them to clone mode?
We disable cloning of certain encoders in the driver. At the hardware level, you can source multiple encoders to the same crtc, but there are too many encoder specific limitations in most cases that make it hard to support cloning from the same crtc. DP and LVDS are not possible for example as they use different clocking for the encoders. LVDS is direct clocked from the PPLL while DP uses fixed clock derived from the DCPLL, so you can't drive both off the same crtc easily, at least not the way the driver is currently structured.
That would also explain why I still have a moving tear line even when using exactly the same modeline on both - their base clock seems to differ slightly.
Currently both Xv and GL sync to LVDS by default, no matter which output is primary, and no matter which CRTC they use: Even if DP is primary and CRTC 0, sync is on LVDS.
You might try assigning primary flag to the DP output. xrandr --output DisplayPort-0 --primary
That's what I tried, but both GL and Xv still sync to LVDS?