broken edid

[Gerd Hoffmann]

  Hi,

Apparently something corrupted the hdmi edid of the monitor I've hooked
up to the rpi3.  So the firmware comes up in some low res instead of
1920x1080, and vc4 complains and refuses to display anything.

Tried to fix the edid.  Reading (via /dev/i2c-2) works.  Writing fails
with an io error though, there is even a message in the kernel log
(i2c-bcm2835 3f805000.i2c: i2c transfer failed: 100).  I'm using
https://github.com/bulletmark/edid-rw.  4.9.16 kernel.  Ideas anyone?

Failing that, is there some way to force vc4 into driving hdmi at
1920x1080?

cheers,
  Gerd