nanopi-r76s: fix slow WiFi by enabling SDIO SDR104

[SuperKali]

Description

The R76S WiFi (RTL8822CS on M.2 SDIO) never came up in UHS. The card runs on a fixed-1.8V rail yet still sets S18A=1, so the core sent CMD11. There is no real voltage transition to make, the dw_mmc clock update times out, and the bus drops to high speed.

The fix skips that switch when the host already signals 1.8V, matching the guard in mmc_sd_init_card(). It lands in current, edge and bleedingedge. cap-sd-highspeed on the node keeps a 50MHz path if SDR104 tuning ever fails.

How Has This Been Tested?

Built edge (7.0.11), flashed on an R76S, iperf3 over WiFi to the gateway.

• Before: high speed SDIO card at 50MHz, ~51 down / ~23 up Mbit/s
• After: UHS-I speed SDR104 SDIO card at 198MHz, ~210 down / ~52 up Mbit/s

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings

Summary by CodeRabbit

Release Notes

• New Features

  • Added SD high-speed mode support for SDIO controllers across multiple kernel versions.

• Bug Fixes

  • Fixed redundant voltage-switch sequences that could cause controller stalls when initializing certain SDIO cards already configured at 1.8V.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

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Review profile: CHILL

Plan: Pro

Run ID: b4a9a7a7-a338-4553-8342-891859bcf280

📥 Commits

Reviewing files that changed from the base of the PR and between 107075b and babdcec.

📒 Files selected for processing (6)

• patch/kernel/archive/rockchip64-6.18/dt/rk3576-nanopi-r76s.dts
• patch/kernel/archive/rockchip64-6.18/mmc-sdio-skip-cmd11-voltage-switch-when-already-1v8.patch
• patch/kernel/archive/rockchip64-7.0/dt/rk3576-nanopi-r76s.dts
• patch/kernel/archive/rockchip64-7.0/mmc-sdio-skip-cmd11-voltage-switch-when-already-1v8.patch
• patch/kernel/archive/rockchip64-7.1/dt/rk3576-nanopi-r76s.dts
• patch/kernel/archive/rockchip64-7.1/mmc-sdio-skip-cmd11-voltage-switch-when-already-1v8.patch

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📝 Walkthrough

Walkthrough

This PR adds SD high-speed support to the RK3576 NanoPI R76S device-tree configuration and prevents redundant 1.8V voltage switching during SDIO initialization. Both changes are applied consistently across kernel versions 6.18, 7.0, and 7.1.

Changes

SDIO Capabilities and Voltage-Switch Fixes

Layer / File(s)	Summary
Add SD high-speed capability to SDIO device-tree patch/kernel/archive/rockchip64-6.18/dt/rk3576-nanopi-r76s.dts, patch/kernel/archive/rockchip64-7.0/dt/rk3576-nanopi-r76s.dts, patch/kernel/archive/rockchip64-7.1/dt/rk3576-nanopi-r76s.dts	The &sdio node is updated to include cap-sd-highspeed property across kernel versions 6.18, 7.0, and 7.1, enabling SD high-speed mode support.
Skip redundant 1.8V voltage switch in SDIO init patch/kernel/archive/rockchip64-6.18/mmc-sdio-skip-cmd11-voltage-switch-when-already-1v8.patch, patch/kernel/archive/rockchip64-7.0/mmc-sdio-skip-cmd11-voltage-switch-when-already-1v8.patch, patch/kernel/archive/rockchip64-7.1/mmc-sdio-skip-cmd11-voltage-switch-when-already-1v8.patch	The mmc_sdio_init_card() function is patched across kernel versions 6.18, 7.0, and 7.1 to add a guard that prevents issuing CMD11 voltage switch when the host is already at 1.8V, preventing potential controller stalls.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested labels

Ready to merge, 05

Suggested reviewers

• joekhoobyar
• krachlatte
• pyavitz
• rpardini
• TheSnowfield
• brentr

Poem

🐰 A rabbit hops through kernel trees so tall,
Device-trees bloom with cap-sd-highspeed call,
While voltage guards skip redundant CMD11 dance,
Three kernel paths get their RK3576 chance,
High-speed SDIO now flows without a stall! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: enabling SDIO SDR104 for WiFi performance improvement on the R76S board.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

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