Google Nexus 6P (huawei-angler)

== Contributors ==
* zhuowei, khimaros, Learn Chung Chen
== Users owning this device ==
== How to enter flash mode ==
* Connect a USB cable
* Make sure, the device is powered off
* Hold power + volume down
* Continue holding until you se the bootloader menu
==pmbootstrap install==
Install pmbootstrap and then run:
$ pmbootstrap init
$ pmbootstrap install
$ pmbootstrap flasher flash_rootfs
$ pmbootstrap flasher flash_kernel
== Kernel configs applied ==
Configs changed from stock Lineage kernel:
* CONFIG_DEVTMPFS=y
* CONFIG_VT=y
* CONFIG_FRAMEBUFFER_CONSOLE=y
* Various NFS client configs: CONFIG_NFS_V4_1=y
* CONFIG_BCMDHD_FW_PATH, CONFIG_BCMDHD_NVRAM_PATH
== How to enter flash mode ==
The Nexus 6P, like all Google Nexus devices, uses Fastboot as the flashing protocol.
To enter Fastboot mode, hold Volume Down while powering on the device. Let go of Volume Down when a picture of a green Android mascot shows up on the screen.
== Limitations ==
The Nexus 6P running on downstream kernel does not have DRM support, which means most accelerated interfaces (such as phosh and sway) are unsupported. There are two known workarounds:
* Recommended: running wlroots based compositors using wlroots native x11/fbdev + pixman support: relies purely on existing upstream behavior with a minor bug fix patch against wlroots.
* Run wlroots with fbdev: relies on a custom fbdev backend for wlroots which has been declined for upstream inclusion.
== Research ==
=== Mainline ===
There was an initial project to port the mainline kernel to Nexus 6P. As a result there's now some support for Nexus 6P in mainline. Later more functionality was added to msm8994, but just some of that is used in Angler. For more info see mainline section of the chipset.
=== Modem ===
Android boots the modem by mounting the modem partition to /firmware, then opening /dev/subsys_modem. Doing the same on postmarketOS (after linking all the firmware in /firmware/images to /lib/firmware/postmarketos) causes any `dmesg` call to freeze (?!), and the device would kernel panic with a "modem crashed" error in a few seconds.
=== Audio ===
The audio requires the blobs from Android's /vendor/adsp.* to be present in /lib/firmware/postmarketos. Then, opening /dev/subsys_adsp will boot the sound card. Currently ALSA recognizes the sound card but fails with an error when playing audio: the Android audio configuration files would need to be converted to Linux format by xml2ucm. See https://arunraghavan.net/2016/01/audio-devices-and-configuration/ for an explanation of the difference between Android and Linux audio, and see https://github.com/kholk/sony-alsa-ucm/tree/master/kitakami for a different SD810 device's ALSA config.
=== Bluetooth ===
It seems Bluetooth is connected via H4 UART at /dev/ttyHS0. Tizen uses the hciattach_bcm43xx tool from BlueZ to load firmware to the Bluetooth dongle, but I can't find this utility in Alpine's bluez or bluez-deprecated package. btattach -B /dev/ttyHS0 doesn't seem to work.
== Links ==
* 
* (downstream)
* (close to mainline kernel – alternative to downstream kernel, only basic hardware support), added in 
* Merge Request : initial MR
* Merge Request : Wi-Fi and graphics
* Mainline DTS – msm8994-huawei-angler-rev-101.dts
* Downstream kernel (LineageOS 14.1)
* Google Nexus 5X (lg-bullhead) – similar device