Qualcomm Snapdragon 820/821 (MSM8996)

MSM8996/APQ8096 (or Snapdragon 820) is a Qualcomm SoC released in 2016, with great mainline support orginally added for the Dragonboard 820c. There is also a slightly higher clocked (and supposedly less problematic architecture-wise) MSM8996Pro also known as Snapdragon 821.

Porting to a new device
Getting mainline to boot on MSM8996 devices is generally a straightforward process. Check the mainlining guide to get started:

Booting
On at least the Xiaomi Mi Note 2, some IOMMU hacks (1, 2) are needed to let it to boot properly. Otherwise it would crash and reboot as soon as the MDP SMMU is probed.

USB
Enabling  or   depending on which one the USB port is connected to should be enough to make USB work, although forcing it to peripheral mode might be needed before adding support for extcon: MSM8996 USB peripheral mode configuration &usb3 { ... 	dwc3@6a00000 { dr_mode = "peripheral"; ... 	}; };

Some devices have a USB 2.0 port wired to. In this case it must be limited to high-speed and have  removed from it:

MSM8996 USB 2.0 configuration &usb3 { /* Disable USB3 pipe_clk requirement */ qcom,select-utmi-as-pipe-clk; ... 	dwc3@6a00000 { /* usb3-phy is not used on this device */ phys = <&hsusb_phy1>; phy-names = "usb2-phy"; /* Limit USB to high-speed */ maximum-speed = "high-speed"; ... 	}; };

Haptics
Haptics are supported, see Haptics for more details.

Who's working on it

 * User:Tooniis (@tooniis on Matrix)
 * User:WolfLink115 (@WolfLink115 on Telegram, @WolfLink115#4777 on Discord)