Radxa E52C: add mainline U-Boot support and kernel target configuration

[okrc]

Summary by CodeRabbit

• New Features

  • Added comprehensive support for Radxa E52C board equipped with RK3582 processor, including U-Boot and kernel configurations.
  • Introduced RK3582 chip support with device tree customization based on hardware configuration.

• Documentation

  • Updated Rockchip boards documentation to include Radxa E52C in supported boards list.

Testing by schwar3kat

• Build completed successfully
• Tested on real hardware radxa-e52c
• Current - Trixie minimal, Noble minimal
• Edge - Trixie minimal, Noble minimal
• Vendor - Trixie minimal, Noble minimal
• Boot, reboot, shutdown verified
• Network both ports

[coderabbitai]

📝 Walkthrough

Walkthrough

This pull request adds support for the Radxa E52C board powered by the RK3582 SoC. Changes include board configuration with mainline U-Boot support, initial RK3582 support in U-Boot with OTP-based device tree fixups, generic RK3588 configuration updates, and Radxa E52C-specific device tree and defconfig files.

Changes

Cohort / File(s)	Summary
Board Configuration config/boards/radxa-e52c.conf	Updated kernel targets to include multiple branches; added serial console default; introduced mainline U-Boot support functions that override boot-related settings and configure BTRFS.
RK3582 Core Support patch/u-boot/v2026.01/board_radxa-e52c/0000-add-initial-rk3582-support.patch	Added ft_system_setup() function with OTP-based device tree fixups; defines CPU code and ip-state constants; filters RK3582 variants and disables/fails hardware blocks (CPU clusters, GPU, codec) based on OTP policies; provides FDT path manipulation helpers.
Generic RK3588 Updates patch/u-boot/v2026.01/board_radxa-e52c/0001-rk3588-generic-support-for-rk3582.patch	Enabled OF_SYSTEM_SETUP in generic RK3588 defconfig; updated device tree model string and documentation to reflect RK3582/RK3588S/RK3588 support.
Radxa E52C Board Support patch/u-boot/v2026.01/board_radxa-e52c/1000-add-support-for-radxa-e52c.patch	Added Radxa E52C device tree source, board defconfig, and updated Rockchip board documentation listing.

Sequence Diagram

sequenceDiagram
    participant UBoot as U-Boot
    participant OTP as OTP Hardware
    participant FDT as Device Tree
    
    UBoot->>OTP: Read CPU code from OTP offset
    OTP-->>UBoot: Return CPU code value
    alt CPU code matches RK3582
        UBoot->>OTP: Read ip-state (failed/disabled blocks)
        OTP-->>UBoot: Return ip-state bitmask
        UBoot->>UBoot: Apply disable policy based on FAIL_* masks
        alt Cluster disabled
            UBoot->>FDT: Remove/rename cpu-map clusters
        end
        alt GPU/Codec disabled
            UBoot->>FDT: Fail gpu@, video-codec@, iommu@ nodes
        end
        UBoot->>FDT: Append rk3582 to soc-compatible
    end

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 New E52C joins the fold,
With RK3582 brave and bold,
OTP reads what's true,
Device trees fixed anew,
Mainline U-Boot takes control! 🚀

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title directly reflects the main changes: adding mainline U-Boot support and kernel target configuration for the Radxa E52C device, which aligns with the core modifications across all files.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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[coderabbitai]

Actionable comments posted: 0

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

config/boards/radxa-e52c.conf (1)

1-1: ⚠️ Potential issue | 🟡 Minor

Board description says "octa core" but RK3582 is a 6-core SoC.

The RK3582 has 2× Cortex-A76 + 4× Cortex-A55 = 6 cores (confirmed by the patch commit message at line 10 of 1000-add-support-for-radxa-e52c.patch and the OTP/policy output showing 2 CPU cores failed from the RK3588's 8). Also, "SoC" appears twice in the description.

Proposed fix

-# Rockchip RK3582 SoC octa core 4-16GB SoC eMMC USB3
+# Rockchip RK3582 hexa core 4-16GB SoC eMMC USB3

🧹 Nitpick comments (1)

patch/u-boot/v2026.01/board_radxa-e52c/0000-add-initial-rk3582-support.patch (1)

161-176: cluster1_removed is set unconditionally — fine in practice, but fragile if the DT structure were ever unexpected.

On line 165, cluster1_removed = true executes regardless of whether fdt_path_del_node succeeded. If the cluster1 node were absent from the DT, this would still trigger the cluster2 → cluster1 rename at line 175, which would also silently fail. Functionally harmless since the RK3588 DT is expected to always have cluster0/1/2, but a guard could prevent a misleading rename attempt.

This is a very minor robustness nit on an upstream-authored patch, so no change is necessary.

Optional: guard `cluster1_removed` on success

 	if ((ip_state[0] & FAIL_CPU_CLUSTER1) == FAIL_CPU_CLUSTER1) {
 		log_debug("remove cpu-map cluster1\n");
-		fdt_path_del_node(blob, "/cpus/cpu-map/cluster1");
-		cluster1_removed = true;
+		if (!fdt_path_del_node(blob, "/cpus/cpu-map/cluster1"))
+			cluster1_removed = true;
 	}

[schwar3kat]

I will build images and test this on radxa-e52c board.
Done.

[rpardini]

Nice. Maybe you could run ./compile.sh BOARD=radxa-e52c BRANCH=edge rewrite-uboot-patches and commit, so we avoid churn down the line. Although I suspect those will land in 24.04 so quite optional

[schwar3kat]

Tested okay on the board.

[github-actions]

✅ This PR has been reviewed and approved — all set for merge!