boards: pocketbeagle2: Enable USB serial

[Ayush1325]

• Enable USB serial by default.
• Allows serial access without needing extra UART cable.
• Also USB serial is much faster than using the UART debug port.
• Using g_cdc instead of g_serial for sharing network by default (coming once I can test things on windows) as described in the post here: https://gist.github.com/nikp123/c658b31c45288b55141c9d19ede78e6c

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
• Any dependent changes have been merged and published in downstream modules

[coderabbitai]

Walkthrough

The configuration file for the PocketBeagle 2 board was updated to support an additional serial console device. The SERIALCON variable now lists both ttyS2 and ttyGS0, instead of just ttyS2. The kernel command line (SRC_CMDLINE) was modified to add a console entry for ttyGS0 and to include directives to load the dwc2 and g_cdc kernel modules at boot, enabling USB gadget functionality and an extra serial interface.

Possibly related PRs

• beagle: Enable modules for ethernet and serial over USB #8324: Adds kernel USB modules for Ethernet and serial over USB, which is closely related to enabling USB serial functionality in the PocketBeagle 2 board configuration.

Suggested labels

05, Needs review, size/small, Hardware

Suggested reviewers

• Grippy98
• igorpecovnik

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📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between e470ebe and f68fc30.

📒 Files selected for processing (1)

• config/boards/pocketbeagle2.conf (1 hunks)

🧰 Additional context used

🧠 Learnings (2)

📓 Common learnings

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/boards/pocketbeagle2.conf (8)

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.

Learnt from: djurny
PR: armbian/build#8272
File: config/bootscripts/boot-mvebu.cmd:182-186
Timestamp: 2025-06-04T23:45:38.860Z
Learning: In config/bootscripts/boot-mvebu.cmd, the `fdtfile` variable is mandatory for booting and is pre-set by U-Boot, but can be overridden via armbianEnv.txt. If `fdtfile` is empty, the subsequent device tree file search logic will eventually fail and trigger the critical error "Cannot find DT!" with proper error handling.

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: Grippy98
PR: armbian/build#8152
File: lib/functions/configuration/interactive.sh:209-266
Timestamp: 2025-05-05T12:35:07.143Z
Learning: For the interactive kernel selection in Armbian, KERNEL_MAJOR_MINOR and KERNEL_DESCRIPTION are parsed from family.conf but deliberately not set as environment variables to avoid potential interference with other parts of the build system.

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: djurny
PR: armbian/build#8287
File: config/bootscripts/boot-sunxi.cmd:13-23
Timestamp: 2025-06-12T21:08:11.318Z
Learning: In config/bootscripts/boot-sunxi.cmd the variable name `align_overlap_oboe_avoidance` intentionally uses the acronym “OBOE” (Off-By-One Error); it is not a typo and should not be renamed.

Learnt from: Grippy98
PR: armbian/build#8202
File: config/desktop/trixie/environments/gnome/armbian/create_desktop_package.sh:2-3
Timestamp: 2025-05-16T15:34:34.672Z
Learning: The shell scripts in the Armbian build system's desktop configuration files, such as config/desktop/trixie/environments/gnome/armbian/create_desktop_package.sh, rely on environment variables like $SRC and $destination that are expected to be set externally before the script is executed.

⏰ Context from checks skipped due to timeout of 90000ms (2)

• GitHub Check: Shell script analysis
• GitHub Check: Check kernel security options

🔇 Additional comments (2)

config/boards/pocketbeagle2.conf (2)

13-13: LGTM: USB serial console addition is correctly configured.

The addition of ttyGS0 to the serial console configuration enables USB serial functionality as intended. The comma-separated format is correct for specifying multiple serial consoles in Armbian board configurations.

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16-16: LGTM: Kernel command line changes align with USB serial enablement.

The modifications are well-structured and achieve the PR objectives:

1. Console configuration: Adding console=ttyGS0,115200n8 maintains consistency with the SERIALCON variable and provides the same baud rate as the primary console.

2. Module loading: The modules-load=dwc2,g_cdc directive correctly loads:

   • dwc2: USB controller driver for the AM62 SoC
   • g_cdc: USB CDC gadget driver, switching from g_serial to enable network sharing capabilities

This configuration enables faster USB serial access without requiring additional UART cables, as specified in the PR objectives.

✨ Finishing Touches

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