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Xiaomi Redmi Note 8T (xiaomi-willow)

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Revision as of 20:43, 13 June 2020 by Robante15 (talk | contribs)
Xiaomi Redmi Note 8T
Redmi Note 8T running firefox and weston-smoke (kapton tape holding UART in place)
Redmi Note 8T running firefox and weston-smoke (kapton tape holding UART in place)
Manufacturer Xiaomi
Name Redmi Note 8T
Codename xiaomi-willow
Released 2019
Hardware
Chipset Qualcomm SDM665 Snapdragon 665
CPU Octa-core (4x2.0 GHz Kryo 260 Gold & 4x1.8 GHz Kryo 260 Silver)
GPU Adreno 610
Display 1080 x 2340 IPS LCD
Storage 32GB, 64GB, 128GB
Memory 3GB, 4GB, 4GB
Architecture aarch64
Software
Original software Android 9, MIUI 10
postmarketOS
Category testing
Pre-built images no
postmarketOS kernel 4.14.117
Unixbench Whet/Dhry score 4168.2
Features
Flashing
Works
USB Networking
Works
Internal storage
No data
SD card
No data
Battery
No data
Screen
Partial
Touchscreen
Works
Multimedia
3D Acceleration
Broken
Audio
No data
Camera
No data
Camera Flash
No data
Connectivity
WiFi
Broken
Bluetooth
No data
GPS
No data
NFC
No data
Modem
Calls
No data
SMS
No data
Mobile data
No data
Miscellaneous
FDE
No data
USB OTG
Works
HDMI/DP
No data
Sensors
Accelerometer
No data
Magnetometer
No data
Ambient Light
No data
Proximity
No data
Hall Effect
No data
Haptics
No data
Barometer
No data


Contributors

Maintainer(s)

Users owning this device


Note

This device is quite similar to the Xiaomi Redmi Note 7 (xiaomi-lavender), and many of the issues were solved with steps from that device page, so if you're hacking on the 8T it's a good idea to read the xiaomi-lavender page closely.

How to enter flash mode

Unlocking the bootloader

As with any Xiaomi device, in order to unlock the bootloader you need to sign up for a Mi Account, register your device through the MIUI Settings app (requires a working SIM inserted, but only for a few moments), and wait a week. The official Xiaomi tool only runs on Windows, but XiaoMiTool V2 worked for me on Debian Linux. Be careful, it's a closed source jar!

Before you go further

You are strongly recommended to install TWRP and back up ALL partitions to a safe place! (you can adb pull the images from twrp)

Entering recovery

Hold Volume Up + Power until you see the recovery screen.

Entering fastboot

Hold Volume Down + Power until you see the fastboot screen.

Installation

  • Install pmbootstrap.
  • pmbootstrap -y zap; pmbootstrap init, choose xiaomi-willow as your device
    • firmware is currently needed for tianma touchscreen
    • weston is currently the only tested display server
  • pmbootstrap install
  • Enter fastboot, plug USB into computer
  • pmbootstrap flasher flash_kernel
  • pmbootstrap flasher flash_rootfs
  • pmbootstrap flasher flash_vbmeta
  • Reboot, sometimes fastboot reboot works, otherwise hold down Power until it reboots to system.
  • Hopefully weston comes up with postmarketos-demos.
  • ssh user@172.16.42.1

You can also use pmbootstrap flasher boot to boot the kernel/initramfs without flashing.

What's broken

  • Restarting the display server will fail (due to panel power issues?)

UART

Necessary: reasonably fine soldering iron tip, steady hand

Highly recommended: microscope, steadier hand

  • Disassemble the phone. Here's a decent video.
  • I spent way too much time heating up the rubber and trying to use a suction cup. The glue is quite strong, and after heating up the edges to unreasonable temperatures I still couldn't pull the glass off with a suction cup. The key is to heat up the bottom a bit (around 100-150C) and use an extremely thin piece of metal to slide in the bottom and tear the rubber a bit. Then you can keep heating the edges and work your way around the perimeter.
  • After removing the glass, remove the ~12ish green screws holding the upper panel in place. One is hidden under a sticker. Pop the panel off with more prying, as gently as you can but some force will be needed.
  • This is the end of disassembly, the test points are now exposed.
  • Solder as shown in diagram.
  • Test connectivity between everything to make sure there's no shorts.
  • Connect to your favorite UART adapter. It expects 1.8v, but I used this adapter that only goes down to 3.3v, and it hasn't bricked yet.
  • screen /dev/ttyUSB0 115200

Partition Table

xiaomi-willow:~# gdisk -l /dev/mmcblk0 # EXPANDME

Additional Info

Info from the Note 7 port that also applies to the 8T:

Kernel config

  • Disabled CONFIG_RNDIS_IPA because it panics at boot if CONFIG_USB_CONFIGFS_RNDIS is set. IPA seems to be an IP offload IC (?) that will route RNDIS straight to the modem with RMNET (?) over BAM (?).

See also