Adjusting aperture, ISO and shutter speed manually? Huawei P9

Contrary to standalone digital cameras, most smartphones have a fixed aperture due to concerns such as device thickness. P9 is no exception, and is equipped with a f/2.2 fixed aperture lens. Under the "DoF control" mode in the stock camera app, different apertures are simulated using the data captured simultaneously from two camera sensors.

Since it's not a hardware implementation of aperture, it's unlikely any 3rd-party software will be able to make use of it (proprietary algorithm). As of now, unless Huawei themselves decide to add such feature to the stock camera through an update later, you're out of luck.