I found 2 I2C interfaces in the 40-pin low speed expansion connector, marked as I2C0_SCL_1V8, I2C0_SDA_1V8, I2C2_SCL_1V8 and I2C2_SDA_1V8 in schematic. But when I measured these pins without connecting to any thing, I2C0_SCL_1V8 shows a 118KHz wave, and other pins just kept high (1.8V). also when I executed i2cdetect -r 0, nothing showed on the I2C0_SDA_1V8 pin.
I assume this is abnormal for an I2C bus, so what should I do to enable at least I2C0? I notice the pull up resistance R235-R238 are not connected, does it matter?
I’m using the latest kernel/u-boot/l-loader/atf codebase from github, and enabled CONFIG_I2C_CHARDEV for user space programming.