Hello Johannes,
This was due to the corruption that took place, when I rewrote the i2c routines to use irq based transmission. I reliably got debi oops messages and later a TS lockup, so I gave up my efforts.Anyway, IIRC Michael Hunold once told me that he had a hard time getting I2C to work reliably. Maybe he just ran out of patience fiddling with that stuff once it worked...