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HTC Desire 820 Dual SIM (htc-a51dtul): Difference between revisions

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== Users owning this device ==
== Users owning this device ==

Revision as of 23:45, 26 June 2023

This device is marked as not booting.
HTC Desire 820 (Dual SIM)
Manufacturer HTC
Name Desire 820 (Dual SIM)
Codename htc-a51dtul
Released 2014
Hardware
Chipset Qualcomm Snapdragon 615 (MSM8939)
CPU 4x 1.5GHz Cortex-A53 + 4x 1.0GHz Cortex-A53
GPU Adreno 405
Display 720x1280 SLCD
Storage 16GB
Memory 2GB
Architecture aarch64
Software
Original software Android 4.4
postmarketOS
Category testing
Pre-built images no


Contributors

Users owning this device


How to enter flash mode

In Power off state, use Volume- & power key to enter Hboot, and directly select the fastboot interface. Seems this fastboot interface can't use general fastboot for flashing partition, need to use another method to flash.

Installation

"The device must as S-OFF mode for installing custom kernel!"

lk2nd

It appears that using custom .dts as shown in MSM8916 Mainlining#lk2nd didn't succeed so far, lk2nd keeps showing unknown model. Prebuilt lk2nd-msm8916-appended-dtb.img flashed in HTC fastboot mode boots and seems to work. There are two issues though:

  • After flashing the device will stay stuck in HTC fastboot. I've found two ways to get out of this state:
    • Select HBOOT, choose recovery, then reboot into system.
    • If the above is not possible (TWRP images seem scarce for this model) choose power down in HTC fastboot, plug charger, then once animated screen is shown hold power button. Phone should reboot into lk2nd.
  • Button mapping is incorrect - volume up scrolls selection one way (possibly mapped as volume up), power scrolls another (possibly mapped as volume down), volume down does nothing. Haven't found a way to select an option.
  • Running fastboot reboot in both HTC and lk2nd fastboot causes device to reboot into HTC fastboot and get stuck there.

UART

You can connect to the ground by soldering to the pin shown in picture above or just using some part of the motherboard's ground plane, e.g. a screw hole or the large copper shielding. Be aware that UART high level (logical 1) is 1.8 V. UART decoder settings: baud rate - 115200, parity - none, data bits - 8.

Notes

  • this device is named as Desire 820u (d820u), not d820s
  • the system image is same as Desire 820 Single SIM, but device tree image is different.