feat: Add CONFIG_BACKLIGHT_GPIO=m for TinyDRM backlight #8366
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This is required for gpio-backlight when using the Tiny DRM driver with SPI-interface LCD panels
d93921012
requested review from
TheSnowfield,
Tonymac32,
janprunk,
leggewie and
sgjava
as code owners
WalkthroughThe pull request updates three kernel configuration files for the sunxi platform: Assessment against linked issues
Assessment against linked issues: Out-of-scope changesNo out-of-scope changes were found. Possibly related issues
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Actionable comments posted: 0
🧹 Nitpick comments (1)
config/kernel/linux-sunxi-current.config (1)
1684-1690: Consider makingBACKLIGHT_GPIObuilt-in to guarantee early backlight availabilityThe reported issue occurs during early panel initialisation.
BuildingCONFIG_BACKLIGHT_GPIOas a module means the driver is not available until userspace loads modules, which can still leave the panel without a back-light during the crucial early boot sequence and may continue to trigger the “deferred probe” path on some boards.If size isn’t a concern, switching it to built-in (
=y) is safer:-CONFIG_BACKLIGHT_GPIO=m +CONFIG_BACKLIGHT_GPIO=yOtherwise, ensure the module is included in the initramfs or that
modules-load.dpulls it in early enough.
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📒 Files selected for processing (3)
config/kernel/linux-sunxi-current.config(1 hunks)config/kernel/linux-sunxi-edge.config(1 hunks)config/kernel/linux-sunxi-legacy.config(1 hunks)
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🧠 Learnings (4)
📓 Common learnings
Learnt from: EvilOlaf
PR: armbian/build#8328
File: lib/functions/compilation/patch/drivers_network.sh:542-545
Timestamp: 2025-06-24T10:08:40.313Z
Learning: In the Armbian build system, when a PR removes build support for a specific kernel version, version check issues for that removed version become practically irrelevant even if they appear incorrect in isolation. Context about which kernel versions are being deprecated/removed is important for understanding the impact of version-related code changes.
Learnt from: rpardini
PR: armbian/build#8044
File: patch/u-boot/v2025.04/cmd-fileenv-read-string-from-file-into-env.patch:76-86
Timestamp: 2025-03-31T22:20:48.475Z
Learning: For the Armbian build project, maintaining consistency with existing patches across U-Boot versions (such as between 2025.01 and 2025.04) is prioritized over refactoring individual patches for code improvements.
Learnt from: pyavitz
PR: armbian/build#8361
File: config/kernel/linux-sunxi64-edge.config:594-597
Timestamp: 2025-07-06T16:27:45.349Z
Learning: In Armbian sunxi64-edge kernel configurations, PCI/PCIe support may be enabled for future-proofing purposes to support upcoming Allwinner SoCs like the T536 that include PCIe Gen2 interfaces, even if current primary targets like H616 lack PCIe controllers. This forward-looking approach prepares the configuration for next-generation hardware in the same SoC family.
Learnt from: EvilOlaf
PR: armbian/build#8330
File: config/sources/families/sun55iw3.conf:32-36
Timestamp: 2025-06-25T03:42:09.086Z
Learning: In Armbian build system configuration files like config/sources/families/*.conf, KERNELSOURCE is explicitly declared when using unofficial or 3rd party kernel repositories (like the "dev" branch using https://github.com/apritzel/linux), but can be omitted when using the standard mainline kernel (like the "edge" branch) since it will fall back to the default mainline source.
config/kernel/linux-sunxi-legacy.config (4)
Learnt from: pyavitz
PR: armbian/build#8361
File: config/kernel/linux-sunxi64-edge.config:594-597
Timestamp: 2025-07-06T16:27:45.349Z
Learning: In Armbian sunxi64-edge kernel configurations, PCI/PCIe support may be enabled for future-proofing purposes to support upcoming Allwinner SoCs like the T536 that include PCIe Gen2 interfaces, even if current primary targets like H616 lack PCIe controllers. This forward-looking approach prepares the configuration for next-generation hardware in the same SoC family.
Learnt from: EvilOlaf
PR: armbian/build#8330
File: config/sources/families/sun55iw3.conf:32-36
Timestamp: 2025-06-25T03:40:52.109Z
Learning: In Armbian build system configuration files like config/sources/families/*.conf, when KERNELSOURCE is not explicitly declared in a case branch, the system falls back to a default KERNELSOURCE value, so missing KERNELSOURCE declarations are not critical issues.
Learnt from: EvilOlaf
PR: armbian/build#8330
File: config/sources/families/sun55iw3.conf:32-36
Timestamp: 2025-06-25T03:42:09.086Z
Learning: In Armbian build system configuration files like config/sources/families/*.conf, KERNELSOURCE is explicitly declared when using unofficial or 3rd party kernel repositories (like the "dev" branch using https://github.com/apritzel/linux), but can be omitted when using the standard mainline kernel (like the "edge" branch) since it will fall back to the default mainline source.
Learnt from: EvilOlaf
PR: armbian/build#0
File: :0-0
Timestamp: 2025-06-16T03:24:00.458Z
Learning: In Armbian board configuration files (.csc), the standard pattern is to have only one line as a comment describing the board hardware specifications. This single-line description typically includes the SoC model, core count, RAM options, and key features like connectivity options, storage interfaces, and special features.
config/kernel/linux-sunxi-current.config (3)
Learnt from: pyavitz
PR: armbian/build#8361
File: config/kernel/linux-sunxi64-edge.config:594-597
Timestamp: 2025-07-06T16:27:45.349Z
Learning: In Armbian sunxi64-edge kernel configurations, PCI/PCIe support may be enabled for future-proofing purposes to support upcoming Allwinner SoCs like the T536 that include PCIe Gen2 interfaces, even if current primary targets like H616 lack PCIe controllers. This forward-looking approach prepares the configuration for next-generation hardware in the same SoC family.
Learnt from: EvilOlaf
PR: armbian/build#0
File: :0-0
Timestamp: 2025-06-16T03:24:00.458Z
Learning: In Armbian board configuration files (.csc), the standard pattern is to have only one line as a comment describing the board hardware specifications. This single-line description typically includes the SoC model, core count, RAM options, and key features like connectivity options, storage interfaces, and special features.
Learnt from: EvilOlaf
PR: armbian/build#8330
File: config/sources/families/sun55iw3.conf:32-36
Timestamp: 2025-06-25T03:40:52.109Z
Learning: In Armbian build system configuration files like config/sources/families/*.conf, when KERNELSOURCE is not explicitly declared in a case branch, the system falls back to a default KERNELSOURCE value, so missing KERNELSOURCE declarations are not critical issues.
config/kernel/linux-sunxi-edge.config (4)
Learnt from: pyavitz
PR: armbian/build#8361
File: config/kernel/linux-sunxi64-edge.config:594-597
Timestamp: 2025-07-06T16:27:45.349Z
Learning: In Armbian sunxi64-edge kernel configurations, PCI/PCIe support may be enabled for future-proofing purposes to support upcoming Allwinner SoCs like the T536 that include PCIe Gen2 interfaces, even if current primary targets like H616 lack PCIe controllers. This forward-looking approach prepares the configuration for next-generation hardware in the same SoC family.
Learnt from: EvilOlaf
PR: armbian/build#8330
File: config/sources/families/sun55iw3.conf:32-36
Timestamp: 2025-06-25T03:42:09.086Z
Learning: In Armbian build system configuration files like config/sources/families/*.conf, KERNELSOURCE is explicitly declared when using unofficial or 3rd party kernel repositories (like the "dev" branch using https://github.com/apritzel/linux), but can be omitted when using the standard mainline kernel (like the "edge" branch) since it will fall back to the default mainline source.
Learnt from: EvilOlaf
PR: armbian/build#0
File: :0-0
Timestamp: 2025-06-16T03:24:00.458Z
Learning: In Armbian board configuration files (.csc), the standard pattern is to have only one line as a comment describing the board hardware specifications. This single-line description typically includes the SoC model, core count, RAM options, and key features like connectivity options, storage interfaces, and special features.
Learnt from: libiunc
PR: armbian/build#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.
🔇 Additional comments (2)
config/kernel/linux-sunxi-edge.config (1)
1684-1690: GPIO back-light support correctly enabledAdding
CONFIG_BACKLIGHT_GPIO=mcleanly resolves the missing TinyDRM back-light requirement without conflicting with existing back-light options (e.g.,BACKLIGHT_PWM). Dependencies (BACKLIGHT_CLASS_DEVICE=y) are already satisfied, so the change is safe and self-contained. LGTM.config/kernel/linux-sunxi-legacy.config (1)
1690-1699: Addition makes sense – please double-check there’s no earlierCONFIG_BACKLIGHT_GPIOentryEnabling the GPIO backlight driver as a module is the right fix for TinyDRM panels and is consistent with the other Sunxi configs.
Just verify that the symbol isn’t already defined elsewhere in this file (occasionally legacy configs carry duplicates), otherwise you’re all set.
leggewie
approved these changes
Jul 10, 2025
There was a problem hiding this comment.
Thank you. Looks good.
Just a hint: If you add "Closes: #8362" to the first line of your git commit message github will automatically close the referenced ticket for you once the PR gets merged.
Do you think you can "git commit . --amend ; git push -f" this?
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This is required for gpio-backlight when using the Tiny DRM driver with SPI-interface LCD panels
Description
When using panel-mipi-dbi-spi to connect an SPI-interface LCD panel, the following error occurs:
spi spi0.0: deferred probe pending: panel-mipi-dbi-spi: Failed to get backlightAfter enabling gpio-backlight, it works properly.
GitHub issue reference:
Jira reference number [AR-2708]
How Has This Been Tested?
It was tested on Orange Pi One with kernel 6.6.75, 6.12.30 and 6.15.0
Checklist: