kernel: mvebu: enable tickless idle #9139

neheb · 2025-12-28T01:22:40Z

Switch to NO_HZ_IDLE for energy saving. Also enable Menu cpuidle governor for tickless systems.

Summary by CodeRabbit

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- Updated kernel configuration across MVEBU platforms for improved power management and CPU idle behavior

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Switch to NO_HZ_IDLE for energy saving. Also enable Menu cpuidle governor for tickless systems. Signed-off-by: Rosen Penev <rosenp@gmail.com>

coderabbitai · 2025-12-28T01:22:45Z

📝 Walkthrough

Walkthrough

Kernel configuration files for two mvebu board variants are updated to replace periodic timer support with dynamic tickless idle functionality and switch the CPU idle governor from LADDER to MENU.

Changes

Cohort / File(s)	Summary
Kernel configuration updates (mvebu) `config/kernel/linux-mvebu-edge.config`, `config/kernel/linux-mvebu64-edge.config`	Removed `CONFIG_HZ_PERIODIC=y`; added `CONFIG_NO_HZ_COMMON=y` and `CONFIG_NO_HZ_IDLE=y`; replaced `CONFIG_CPU_IDLE_GOV_LADDER=y` with `CONFIG_CPU_IDLE_GOV_MENU=y`

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Suggested labels

11, BSP

Suggested reviewers

igorpecovnik
pyavitz
krachlatte
JohnTheCoolingFan

Poem

🐰 Tickless timers, now at rest,
MENU's chosen—truly best,
Two boards aligned with idle grace,
Power saving wins the race! ⚡✨

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'kernel: mvebu: enable tickless idle' directly and clearly summarizes the main change—enabling tickless idle functionality in the mvebu kernel configuration by switching to NO_HZ_IDLE mode.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing touches

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📥 Commits

Reviewing files that changed from the base of the PR and between 1e7ef9d and de65658.

📒 Files selected for processing (2)

config/kernel/linux-mvebu-edge.config
config/kernel/linux-mvebu64-edge.config

🧰 Additional context used

🧠 Learnings (14)

📓 Common learnings

Learnt from: igorpecovnik
Repo: armbian/build PR: 8849
File: config/boards/radxa-e54c.csc:14-28
Timestamp: 2025-11-02T20:49:56.719Z
Learning: In Armbian board configuration files (config/boards/*.conf, *.csc, etc.), do not use kernel_config_set, kernel_config_set_m, kernel_config_set_y, or custom_kernel_config__* functions to modify kernel configuration. Kernel configuration is associated with LINUXFAMILY/BOARDFAMILY, not individual BOARD. Board-specific kernel modifications cause inconsistency in kernel packages published to the apt repository because boards within a family share the same kernel packages. Kernel configuration changes must be made in the appropriate kernel config file (e.g., config/kernel/linux-*-*.config) or in family configuration files (config/sources/families/*.conf, *.inc) instead.

Learnt from: tabrisnet
Repo: armbian/build PR: 8678
File: config/kernel/linux-bcm2711-edge.config:859-861
Timestamp: 2025-09-27T21:47:58.020Z
Learning: In the Armbian build system, kernel configuration files in config/kernel/ are generated through an automated process: taking previous config → applying scripted changes from armbian-kernel.sh → running kernel's `make oldconfig` → processing by Armbian machinery back into config files. This automated process properly handles kernel configuration dependencies and reduces the likelihood of manual configuration errors.

Learnt from: tabrisnet
Repo: armbian/build PR: 8678
File: config/kernel/linux-sm8250-current.config:78-80
Timestamp: 2025-09-27T21:49:55.796Z
Learning: In the Armbian build system, kernel configuration files are generated through an automated process: taking previous config → applying scripted changes from armbian-kernel.sh → running kernel's `make oldconfig` → processing by Armbian machinery back into config files. This automated process properly handles kernel configuration dependencies and reduces the likelihood of manual configuration errors.

Learnt from: tabrisnet
Repo: armbian/build PR: 8678
File: config/kernel/linux-sunxi64-current.config:94-94
Timestamp: 2025-09-27T21:50:15.915Z
Learning: When kernel config files are generated through Armbian's automated process (previous config → armbian-kernel.sh changes → make oldconfig → Armbian machinery processing), manual config file edits are not appropriate since they would be overwritten. Deprecated option handling should be implemented in the automated tooling instead.

Learnt from: tabrisnet
Repo: armbian/build PR: 8678
File: config/kernel/linux-sm8250-edge.config:80-82
Timestamp: 2025-09-27T21:50:04.845Z
Learning: In the Armbian build system, kernel configuration files are generated through this automated process: taking previous config → applying scripted changes from armbian-kernel.sh → running kernel's `make oldconfig` → processing by Armbian machinery back into config files. This automated process properly handles kernel configuration dependencies and reduces the likelihood of manual configuration errors.

Learnt from: pyavitz
Repo: armbian/build PR: 8388
File: config/boards/kickpik2b.conf:56-72
Timestamp: 2025-07-17T04:16:29.551Z
Learning: For AIC8800 Bluetooth devices in Armbian board configurations, systemd service configurations intentionally use Type=idle and boot delays because there is no compatibility to load AIC8800 bluetooth in mainline kernel. These delays and service timing are necessary workarounds for hardware limitations rather than performance issues.

Learnt from: tabrisnet
Repo: armbian/build PR: 8746
File: config/kernel/linux-filogic-edge.config:344-470
Timestamp: 2025-10-11T19:52:54.648Z
Learning: The chainsx/linux-filogic kernel (legacy branch) for BPI-R4 uses out-of-tree proprietary drivers (CONFIG_NET_DSA_AN8855, CONFIG_AIROHA_EN8801SC_PHY, CONFIG_AIR_AN8855_PHY, CONFIG_MDIO_AN8855, CONFIG_MFD_AIROHA_AN8855). The frank-w/BPI-Router-Linux kernel (current and edge branches) uses mainline kernel drivers instead: CONFIG_NET_DSA_MT7530 for the DSA switch and CONFIG_MEDIATEK_2P5GE_PHY for PHY support. These provide equivalent functionality for BPI-R4 networking.

📚 Learning: 2025-11-02T20:49:56.719Z

Learnt from: igorpecovnik
Repo: armbian/build PR: 8849
File: config/boards/radxa-e54c.csc:14-28
Timestamp: 2025-11-02T20:49:56.719Z
Learning: In Armbian board configuration files (config/boards/*.conf, *.csc, etc.), do not use kernel_config_set, kernel_config_set_m, kernel_config_set_y, or custom_kernel_config__* functions to modify kernel configuration. Kernel configuration is associated with LINUXFAMILY/BOARDFAMILY, not individual BOARD. Board-specific kernel modifications cause inconsistency in kernel packages published to the apt repository because boards within a family share the same kernel packages. Kernel configuration changes must be made in the appropriate kernel config file (e.g., config/kernel/linux-*-*.config) or in family configuration files (config/sources/families/*.conf, *.inc) instead.

Applied to files:

config/kernel/linux-mvebu-edge.config
config/kernel/linux-mvebu64-edge.config

📚 Learning: 2025-08-30T04:13:16.457Z

Learnt from: tabrisnet
Repo: armbian/build PR: 0
File: :0-0
Timestamp: 2025-08-30T04:13:16.457Z
Learning: Armbian kernel configuration files like linux-filogic-current.config are autogenerated overlays on top of arch defconfig. Comments added manually will be lost during future updates by maintainers, and explicit "CONFIG_OPTION is not set" statements aren't needed for mutually exclusive options since these are overlay configs that only specify changes from the base configuration.

Applied to files:

config/kernel/linux-mvebu-edge.config
config/kernel/linux-mvebu64-edge.config

📚 Learning: 2025-09-27T21:50:15.915Z

Learnt from: tabrisnet
Repo: armbian/build PR: 8678
File: config/kernel/linux-sunxi64-current.config:94-94
Timestamp: 2025-09-27T21:50:15.915Z
Learning: When kernel config files are generated through Armbian's automated process (previous config → armbian-kernel.sh changes → make oldconfig → Armbian machinery processing), manual config file edits are not appropriate since they would be overwritten. Deprecated option handling should be implemented in the automated tooling instead.

Applied to files:

config/kernel/linux-mvebu-edge.config
config/kernel/linux-mvebu64-edge.config

📚 Learning: 2025-09-27T21:47:58.020Z

Learnt from: tabrisnet
Repo: armbian/build PR: 8678
File: config/kernel/linux-bcm2711-edge.config:859-861
Timestamp: 2025-09-27T21:47:58.020Z
Learning: In the Armbian build system, kernel configuration files in config/kernel/ are generated through an automated process: taking previous config → applying scripted changes from armbian-kernel.sh → running kernel's `make oldconfig` → processing by Armbian machinery back into config files. This automated process properly handles kernel configuration dependencies and reduces the likelihood of manual configuration errors.

Applied to files:

config/kernel/linux-mvebu-edge.config
config/kernel/linux-mvebu64-edge.config

📚 Learning: 2025-09-27T21:49:55.796Z

Learnt from: tabrisnet
Repo: armbian/build PR: 8678
File: config/kernel/linux-sm8250-current.config:78-80
Timestamp: 2025-09-27T21:49:55.796Z
Learning: In the Armbian build system, kernel configuration files are generated through an automated process: taking previous config → applying scripted changes from armbian-kernel.sh → running kernel's `make oldconfig` → processing by Armbian machinery back into config files. This automated process properly handles kernel configuration dependencies and reduces the likelihood of manual configuration errors.

Applied to files:

config/kernel/linux-mvebu-edge.config
config/kernel/linux-mvebu64-edge.config

📚 Learning: 2025-09-27T21:50:04.845Z

Learnt from: tabrisnet
Repo: armbian/build PR: 8678
File: config/kernel/linux-sm8250-edge.config:80-82
Timestamp: 2025-09-27T21:50:04.845Z
Learning: In the Armbian build system, kernel configuration files are generated through this automated process: taking previous config → applying scripted changes from armbian-kernel.sh → running kernel's `make oldconfig` → processing by Armbian machinery back into config files. This automated process properly handles kernel configuration dependencies and reduces the likelihood of manual configuration errors.

Applied to files:

config/kernel/linux-mvebu-edge.config
config/kernel/linux-mvebu64-edge.config

📚 Learning: 2025-09-22T21:52:01.225Z

Learnt from: tabrisnet
Repo: armbian/build PR: 8661
File: lib/functions/compilation/armbian-kernel.sh:194-201
Timestamp: 2025-09-22T21:52:01.225Z
Learning: In lib/functions/compilation/armbian-kernel.sh, the kernel_config_modifying_hashes array is not universally required for all kernel configuration functions - some functions like armbian_kernel_config__netkit() operate without it, and adding entries with '=m' would be incorrect when the actual result might be '=y' for options already built-in.

Applied to files:

config/kernel/linux-mvebu-edge.config
config/kernel/linux-mvebu64-edge.config

📚 Learning: 2025-08-02T05:46:10.664Z

Learnt from: EvilOlaf
Repo: armbian/build PR: 0
File: :0-0
Timestamp: 2025-08-02T05:46:10.664Z
Learning: In the Armbian build system, the KERNEL_CONFIGURE=yes switch is deprecated. The recommended approach for kernel configuration is now to use the `kernel-config` build command, which provides a more structured way to configure kernel options.

Applied to files:

config/kernel/linux-mvebu-edge.config

📚 Learning: 2025-10-22T07:56:19.424Z

Learnt from: igorpecovnik
Repo: armbian/build PR: 8789
File: config/kernel/linux-sunxi64-edge.config:839-839
Timestamp: 2025-10-22T07:56:19.424Z
Learning: In Linux kernel configuration, some `=y` (builtin) options are infrastructure or feature flags that enable subsystems or features for modular drivers, rather than directly compiling code into the kernel. For example, in Armbian wireless configs, options like CONFIG_SPARD_WLAN_SUPPORT=y, CONFIG_SC23XX=y, CONFIG_WCN_BSP_DRIVER_BUILDIN=y, CONFIG_UNISOC_WIFI_PS=y are module infrastructure/feature enablers, while the actual drivers (CONFIG_WLAN_UWE5621=m, CONFIG_WLAN_UWE5622=m) remain as loadable modules. These infrastructure options don't cause kernel bloat.

Applied to files:

config/kernel/linux-mvebu-edge.config
config/kernel/linux-mvebu64-edge.config

📚 Learning: 2025-07-27T15:56:34.414Z

Learnt from: pyavitz
Repo: armbian/build PR: 8421
File: config/kernel/linux-sunxi64-edge.config:438-439
Timestamp: 2025-07-27T15:56:34.414Z
Learning: CONFIG_NET_SCH_DEFAULT is a boolean kernel configuration option (=y or =n) that enables/disables the ability to override the default network queueing discipline at runtime. When set to 'y', it allows setting the actual qdisc name via /proc/sys/net/core/default_qdisc at runtime, not in the kernel config file itself.

Applied to files:

config/kernel/linux-mvebu-edge.config
config/kernel/linux-mvebu64-edge.config

📚 Learning: 2025-07-15T21:09:23.252Z

Learnt from: pyavitz
Repo: armbian/build PR: 8383
File: config/kernel/linux-sunxi64-edge.config:57-64
Timestamp: 2025-07-15T21:09:23.252Z
Learning: In Linux kernel configuration, when CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y is set, the ondemand governor is implicitly enabled by default, making the explicit CONFIG_CPU_FREQ_GOV_ONDEMAND=y line redundant. The make menuconfig tool automatically removes such redundant lines. This behavior applies to CPU frequency governor configurations in general - setting a default governor automatically enables that governor.

Applied to files:

config/kernel/linux-mvebu-edge.config
config/kernel/linux-mvebu64-edge.config

📚 Learning: 2025-10-23T19:48:42.980Z

Learnt from: igorpecovnik
Repo: armbian/build PR: 8812
File: config/kernel/linux-sm8250-edge.config:498-501
Timestamp: 2025-10-23T19:48:42.980Z
Learning: For Armbian EDGE kernel configs, CONFIG_ATH12K=m alone is sufficient for PCI-based Wi-Fi 7 devices (e.g., WCN785x/QCN9274). A separate CONFIG_ATH12K_PCI option is not required, as confirmed by maintainer testing.

Applied to files:

config/kernel/linux-mvebu64-edge.config

📚 Learning: 2025-03-31T12:57:13.880Z

Learnt from: libiunc
Repo: armbian/build PR: 8033
File: config/kernel/linux-starfive2-vendor.config:43-43
Timestamp: 2025-03-31T12:57:13.880Z
Learning: For StarFive2 platform kernel configurations, maintain alignment with vendor-provided configurations rather than modifying security settings like SECCOMP. This ensures hardware compatibility as intended by the manufacturer.

Applied to files:

config/kernel/linux-mvebu64-edge.config

🔇 Additional comments (2)

config/kernel/linux-mvebu64-edge.config (1)

7-8: LGTM! Tickless idle configuration is correct.

The addition of CONFIG_NO_HZ_IDLE and switch to CONFIG_CPU_IDLE_GOV_MENU are appropriate changes for enabling tickless idle on the mvebu64 platform. This should improve power efficiency during idle periods by reducing unnecessary timer interrupts. The MENU governor is the recommended choice for tickless systems as it uses predictive algorithms to select optimal idle states.

All required dependencies are properly configured (HIGH_RES_TIMERS is already enabled on line 9).

Also applies to: 61-61

config/kernel/linux-mvebu-edge.config (1)

7-8: LGTM! Changes consistent with mvebu64 variant.

The tickless idle configuration is correctly applied to the 32-bit mvebu platform, matching the changes in the ARM64 variant. The switch to CONFIG_CPU_IDLE_GOV_MENU along with CONFIG_NO_HZ_IDLE is appropriate for energy-efficient operation.

The platform-specific CPU idle drivers (lines 68-69: ARM_CPUIDLE and ARM_MVEBU_V7_CPUIDLE) are already enabled, ensuring proper integration with the new tickless configuration.

Also applies to: 67-67

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tabrisnet · 2025-12-28T01:35:20Z

Nothing obviously wrong. Would want to see the board maintainers pipe in here to see if there's any concerns or history here.
@leggewie @igorpecovnik @Heisath

kernel: mvebu: enable tickless idle

de65658

Switch to NO_HZ_IDLE for energy saving. Also enable Menu cpuidle governor for tickless systems. Signed-off-by: Rosen Penev <rosenp@gmail.com>

neheb requested review from Heisath and igorpecovnik as code owners December 28, 2025 01:22

github-actions bot added 02 Milestone: First quarter release size/small PR with less then 50 lines Needs review Seeking for review Hardware Hardware related like kernel, U-Boot, ... labels Dec 28, 2025

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