I2C1 bus is used for the following peripherals
P8 connector (MLB)
TLV320AIC3106 Audio codec
J15 LCD header
24WC256 eeprom
TMP102AIDRLT temperature sensor
PCF8575 GPIO expander
PCA9306 i2c voltage translator -> Goes to P9 for comm interface
P2 expansion connector
TPS65917 PMIC
The slowest speed of all the peripherals seems to be 400KHz.