Did that and edited my previous post.
Had some idea's come up overnight and found some interesting stuff based on them. The FPGA is used to talk to the unknown I2C chip connected to it and I believe the MCU uses the FPGA commands in the range 0x6X to communicate with this unknown chip.
For the brightness setting in FUN_8001d380 a call is made to FUN_800248f8 with 0x10 and some other parameter. In this function the 0x6X commands are used. There are writes to 0x68 ~ 0x6E. This entails 7 bytes, and what did I find earlier in my quest, the communication with this unknown chip is done in bursts of 8 bytes. 1 slave address and 7 data bytes.
So I have to write an experiment to check this out.
If it is so, things become much clearer. I did notice that the scope remembers it's settings, so we have to identify what each byte used, when calling FUN_800248f8, means.