  The Phase-1 upgrade of the CMS pixel detector is built out of four barrel
layers (BPix) and three forward disks in each endcap (FPix). It comprises a
total of 124M pixel channels in 1,856 modules, and it is designed to withstand
instantaneous luminosities of up to $2 \times 10^{34}\,$cm$^{-2}$s$^{-1}$.
Different parts of the detector were assembled over the last year and later
brought to CERN for installation inside the CMS tracker. At various stages
during the assembly tests have been performed to ensure that the readout and
power electronics and the cooling system meet the design specifications. After
tests of the individual components, system tests were performed before the
installation inside CMS. In addition to reviewing these tests, we also present
results from the final commissioning of the detector in-situ using the central
CMS DAQ system. Finally we review results from the initial operation of the
detector first with cosmic rays and then with pp collisions.
