[Contribution] RK3576 Boot Stability: mkimage v2 support and early-init boost

[th3cavalry]

Overview

I've been working on enabling mainline OpenWrt support for the PhotoniCAT 2 (a commercial RK3576-based portable router). In the process, we stabilized several bootloader improvements that should be directly applicable to Flipper One's "mainline-first" goals.

Disclaimer: Much of this was "vibe coded" during rapid prototyping. However, it is field-tested and fully functional; the device is building, flashing, and booting reliably using these exact patches.

Key Contributions

We ran into several RK3576 BootROM and image alignment quirks that we believe are highly relevant to Flipper One's hardware:

1. Rockchip v2 mkimage Support: We have developed a set of 6 patches that split size_and_off, add support for up to 4 embedded images (e.g., SPL + TPL + OP-TEE), and allow for overriding offset alignments (specifically 4 KiB, which is required for stable UFS operation on this SoC).
2. rk3576-boost.c SPL Initialization: We integrated a "boost" hack that initializes the PMIC (RK806) and ramps CPU/DDR clocks during the SPL phase. This significantly reduces total boot time and mitigates instability during the handoff to the kernel.
3. SD/UFS Alignment Fixes: Specific overrides for image sector counts to ensure the RK3576 BootROM samples the image correctly from removable media.

References

• OpenWrt PR: openwrt/openwrt#22246
• Relevant Patches: See package/boot/uboot-rockchip/patches/116-* in the PR link above.

I am happy to format these as a formal PR against your U-Boot fork if this aligns with your current roadmap.

[alchark]

You may notice that the patches from Jonas Karlman which were submitted in the referenced OpenWRT PR are already part of Git history in this repository.

I don't see any code initializing the PMIC and ramping CPU/DDR clocks as the cover letter says though - would you mind pointing me at those parts?

[th3cavalry]

You may notice that the patches from Jonas Karlman which were submitted in the referenced OpenWRT PR are already part of Git history in this repository.

I don't see any code initializing the PMIC and ramping CPU/DDR clocks as the cover letter says though - would you mind pointing me at those parts?

Good catch, that's my fault for not updating the cover letter!

I originally used a custom rk3576-boost.c file for the early PMIC and clock ramping. However, OpenWrt required me to strip it out to meet their barebones submission policy (noted in my May 11th PR changelog). The patches currently in that link only handle the mkimage packing.

I still have the full PMIC/clock logic locally. How would you like me to submit it when I am able to?