Google Nexus 7 2012 (asus-grouper)

This page documents the status of mainline Linux on the Nexus 7. This document should cover all tablets from first generation (codenamed grouper and tilapia).
Currently all supported features should work as they're supposed to, no known bugs except few not-yet supported features (3D, GPS, cameras and modem).
== Hardware revisions ==
* grouper rev. PM269 - without GSM (older, less frequent)
* grouper rev. E1565 - without GSM (modern)
* tilapia rev. E1565 - with GSM
==== Do I have grouper or tilapia? ====
TWRP (adb shell) $ grep androidboot.baseband=unknown /proc/cmdline && echo grouper || echo tilapia
==== Which hardware revision of grouper do I have? ====
TWRP (adb shell) $ find /sys/devices/ | grep -c max776 && echo You have E1565
TWRP (adb shell) $ find /sys/devices/ | grep -c tps6591 && echo You have PM269
== Flashing ==
When flashing (flashing the kernel or rootfs) the target device must be in flash mode.
=== How to enter flash mode ===
* Connect a USB cable
* Power the device off
* Hold + 
* fastboot should work when the green android appears on the screen
== Hardware status (mainline) ==
There is multiple hardware revisions, so this status may not apply to all of them. This status apply for tilapia (Bach revision).
Status	Hardware 	Info
Y 	Booting 	... but when is kernel larger than approx 4MB, initfs must be packed directly inside kernel (not into boot.img as usual), otherwise kernel won't boot. Older downstream kernels was smaller, so no issue there.
Y 	Touchscreen 	Works.
Y 	USB & USB OTG 	Works.
Y 	SDHCI 	Works.
Y 	NFC 	wired, not tested yet. Please update if it'll work for you.
P 	GPS 	Broadcom BCM4751 GPS is unsupported by the kernel and gpsd. Pangelo works on it.
Y 	WiFi and Bluetooth 	Wi-Fi works (best with IWD daemon: apk add iwd; rc-update del wpa_supplicant; rc-update add iwd; and HOWTO) but 802.11w (management frame protection) must be completely disabled, Bluetooth does work as well (tested with BT 4.2 and 5.0 devices).
Y 	GPIO keys 	There is 3 keys on GPIO: Power, Volume up, Volume down.
Y 	Battery and Charger	Battery status and charging works as expected.
Y 	Sound 	Works, ALSA UCM configs are included into alsa-ucm-conf package
Y 	Temperature sensor 	temperature sensor works
Y 	Proximity sensor 	(tilapia only) Disabled, but works (boolean state, on/off). Would be nice to have this driver work with IIO framework (TODO)
Y 	Light sensor 	Driver Dyna-Image AL3010. Brightness regulation works, install iio-sensor-proxy . It's slightly oversensitive.
N 	Front camera 	
N 	3D support 	See Nvidia_Tegra_2_(tegra20)#Graphics
N 	Modem 	(tilapia only) contribution welcome, no work done yet.
== User Interfaces ==
Multiple, but due to not yet implemented HW acceleration, some of them are currently unavailable (like Phosh)
Recommended interfaces:
* Phosh: Purism Librem 5 compositor and GNOME based environment, needs performance optimization, but works.
* Xfce4: GTK-based desktop environment aiming to be fast and lightweight. Follow the guide at https://wiki.postmarketos.org/wiki/XFCE4 for adjustments.
== Development Notes ==
==== Bootloader ====
* There is some progress on u-boot for Tegra devices. Check u-boot repository
* The default images for android provided by google have the bootloader broken, meaning it can't be flashed. It does not seem to affect the install process of postmarketOS, but is something to take into account. If you need a working bootloader image version 4.23 can be found [here], or can be 4.18 can be grabbed from the factory images for KitKat
==== Kernel ====
Currently used mainline kernel:
* Grate kernel, where tegra development ongoing. It does follow official linux-next branch.
References to older kernels:
* Old Android kernels: LineageOS kernel sources Unlegacy kernel sources
* Ubuntu Nexus 7 Kernel wiki (old, last updated 2012)
==== Graphics ====
* The touchscreen input device is named elan-touchscreen.
* (legacy) CONFIG_VT had to be enabled for graphics to work. In menuconfig this is located under Device Drivers -> Character devices -> Virtual terminal.
* (legacy) /sys/class/graphics/fb0/mode is empty on boot, it must have U:800x1280p-0. This uses the same initfs hook as many other devices. Update: Seems to be correctly set now
* (legacy) weston with fbdev-backend.so uses pixman-type=3 (PIXMAN_TYPE_ABGR), which now does not require configuration.
==== Wifi ====
* There's a proper firmware subpackage now, wifi device should work out-of-the box. 
* "Desktop" Linux firmware are outdated. Check here for latest one.
* To connect follow the instructions on this page.
* (legacy)It is possible to manually get wifi working by manually copying fw_bcmdhd.bin and nvram.txt to their kernel-specified locations and configuring /etc/network/interfaces. At this point, running /etc/init.d/networking restart, gave an error about being unable to get a MAC address. After restarting the device to find that wifi Just Worked™, it was possible to successfully scan for wireless networks and establish a connection to secured wireless APs.
=== Pending Issues ===
* : Use the system and userdata partition on Android with LVM
* : The system partition is too small to hold rootfs images over 650Mb (e.g. Plasma Mobile is about 1.1Gb). Flashing to userdata partition fails.
* : With legacy kernel, device seems to reboot spontaneously under heavy load. For better experience, please use mainline kernel.
= Community Info =
== Users owning this device ==
== Maintainers ==
* David Heidelberg
== Fun Fact ==
grouper was the first tablet to run postmarketOS!
== See also ==
- dmesg logs from various tegra devices https://paste.sr.ht/%7Eokias