Comment 30 for bug 256142

(In reply to comment #29)
> I just tried the latest git (d9df93578b74785c08ba860b4c9aa23b0c89c91c). The
> jittering is still there. However, no black screen so far.

Would you please try to add some new modes toggling the polarity of HSYNC VSYNC to see if there is a mode working?