The EHCI Debug Port is an optional capability of EHCI controllers which can be used for early debugging for hardware which does not have a serial port. All USB2 host controllers are EHCI controllers.
Since I installed Coreboot on my Librem, I experienced some issues. In order to investigate - and since the Librem has no serial port - I aimed to do some Coreboot and kernel debugging with a Raspberry Pi Zero.
The Asus Chromebook Flip C101PA (bob) is a convertible touchscreen laptop powered by an ARMv8 Rockchip RK3399 hexa-core processor and 4GB RAM, measuring 10.4" x 7.2" x 0.6" and weighing 1 kg.
Features:
Rockchip RK3399 (OP1) dual-core 2.0GHz Cortex-A72 and quad-core 1.4GHz Cortex-A53 processor 4GB LPDDR3 RAM 10.1" 1280x800 LED display Mali T860MP4 GPU 16GB eMMC 38 Whrs battery 2x USB 3.1 Type-C ports 1x USB 2.0 Type-A port ARM Chromebooks ship with the Coreboot bootloader and use Depthcharge as the payload.
Radxa Rock 2 Square is a Rockchip RK3288 based solution.
Available images
The available images run with:
A modified version of u-boot The Rabian operating system (which is based on Debian 8) A custom radxa kernel. The goal is to get a pure Debian distribution up and running on the board:
Debian u-boot Debian armhf linux-image kernel Pure Debian root file system For this small project, we have two Radxa Rock 2 Square boards:
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