https://bugs.freedesktop.org/show_bug.cgi?id=17902
--- Comment #82 from thor@math.tu-berlin.de 2012-06-03 10:35:15 PDT --- Got a step further. What one can do to get a stable picture is simply to disable the scaler.
For this, insert: in dvo_ns2501.c, in the function
static void ns2501_mode_set
the following line:
ns2501_writeb(dvo, 0x08, NS2501_8_PD | NS2501_8_BPAS | NS2501_8_VEN | NS2501_8_HEN);
ns2501_dpms should also et the NS2501_8_BPAS bit.
Voila, I get a stable console at boot-up, and a 2D desktop. However, something still seems to be seriously broken outside of the control of the DVO driver. As soon as I start an X session, or a 3D application like tuxracer, the display vanishes. At that point, the DVO also vanishes from the i2c bus for reasons unclear to me. A vbetool post restores the i2cbus.
So at least there seems to be something seriously broken with the i2c communication on this board.
It also happenes that I could start the desktop, but something was wrong with EXA as characters were printed on top of each other (overlayed) instead of erased properly. glxgears seemed to work (at least once).
So what is it with the i2c bus on this system?