The following error message occurs on a 4.4 Linux kernel:

[   28.836018] i2c i2c-7: Invalid 7-bit I2C address 0xff
[   28.908036] i2c i2c-7: failed to add I2C device MSFT8000:00 from ACPI

The reason this happens is because the 4.4 kernel adds an i2c_check_addr_validty call to the acpi_i2c_add_device function. This call returns a failure because that device is defined as having a 7 bit address and an address 0x00ff (which is 8 bits) in the ACPI tables:

            Name (_HID, "MSFT8000")  // _HID: Hardware ID
            Name (_CID, "MSFT8000")  // _CID: Compatible ID
            Name (_UID, One)  // _UID: Unique ID
            Name (_CRS, ResourceTemplate ()  // _CRS: Current Resource Settings
            {
            ...
               I2cSerialBus (0x00FF, ControllerInitiated, 0x00061A80,
                    AddressingMode7Bit, "\\_SB.I2C6",
                    0x00, ResourceConsumer, ,
                    )
            ...