If you are using the board from the Arduino side I will suggest you to take a look at the sketch I attached to this post. It is an I2C scanner. I tested it connecting the Edison Arduino board to an Arduino UNO and to a LCD shield too, and it works.
From Linux side, you could use Python. Here is an example of using I2C from Python: makers-examples/I2Ctest.py at master · MakersTeam/makers-examples · GitHub
If you are using I2C from Linux shell, you have to make sure all the mux settings are set correctly. To see more details about the mux settings, please check this page: EmutexLabs
Let me know if this answered your question. I hope you find this information useful.
I2CScanDevices.ino.zip 655 bytes
Do you have a scanner that scan i2C1 and i2C6 because your programm seems to works only on i2c6.