Looking at upstream I2C support for another platform, I saw we don't have the following changes in chromeos-4.4 (for Baytrail) kernel:

43  c7f82ea86056 i2c: designware-baytrail: fix potential null pointer dereference on dev
53  78c43af2c1d7 i2c-designware: increase timeout of semaphore transfer

Numbers 43/53 come from:

git log --oneline v4.4.. -- drivers/i2c/busses/i2c-designware-\* drivers/i2c/i2c-core.c | nl
     1  9f4659ba3847 i2c: designware: refactor low-level enable/disable
     2  06cb616b1bca i2c: designware: fix poll-after-enable regression
     3  7a20e707aae2 i2c: designware: suppress unneeded SDA hold time warnings
     4  d1fa74520dcd i2c: designware: Consider SCL GPIO optional
     5  fba4adbbf670 i2c: designware: must wait for enable
     6  4141cf676b9e Merge branch 'i2c/for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
...
   159  8d22f309384c i2c: designware: retry transfer on transient failure
   160  04a407f6b129 i2c: dw: Add APM X-Gene ACPI I2C device support
   161  90708ce22b48 i2c: designware: Add support for AMD Seattle I2C
   162  238c44a70c06 i2c: designware: use to_pci_dev()
   163  54177ccfbe95 i2c: make i2c_parse_fw_timings() always visible
   164  e1dba01ca620 i2c: add generic routine to parse DT for timing information
   165  4077a387b79f x86/platform/iosf_mbi: Remove duplicate definitions
   166  4c5301abbf81 i2c: designware: Convert to use unified device property API