There seems to be a resource conflict, accessing the touchpad as PS/2 device
and over I2C

During suspend there is the following in the journal:
psmouse serio1: Failed to disable mouse on isa0060/serio1

After resume:
i2c_designware INT33C3:00: timeout waiting for bus ready
i2c_hid i2c-ATML1000:00: failed to change power setting.
i2c_designware INT33C3:00: timeout waiting for bus ready
i2c_hid i2c-DLL05E3:01: failed to change power setting.

unloading/loading the i2c_designware_platform module leads to the same error
messages.

Unbinding serio1 from psmouse and unloading/loading the dw i2c module restores
the functionality.

HW is a Dell XPS 12 (9Q33)