Stop stream flow document

[ymodlin]

Documentation Issue: Stream Stop Flow in d4xx.c

Summary

Document the complete flow for stopping a video stream in the RealSense D4xx driver (kernel/realsense/d4xx.c).

Motivation

• Help developers understand how the D4xx driver handles stream shutdown and resource cleanup.
• Enable easier debugging, extension, and maintenance of the stop logic.
• Provide a reference for integration with other components and for hardware bring-down.

Tasks

1. Introduction
   • Briefly describe the purpose and context of the stream stop flow.
2. High Level Design
   • Summarize the major steps and components involved in stopping a stream.
   • Use a Mermaid diagram to visualize the flow from user-space request to hardware deactivation.
3. Low Level Design
   • Detail the key functions, data structures, and kernel interactions in d4xx.c.
   • Reference specific code regions and configuration points.
   • Document error handling and edge cases.
4. Integration Points
   • Note interactions with device tree, kernel modules, and user-space APIs.

Example Mermaid Diagram

sequenceDiagram
    participant User
    participant V4L2
    participant D4xx Driver
    participant Hardware
    User->>V4L2: Close video device / VIDIOC_STREAMOFF ioctl
    V4L2->>D4xx Driver: Request stream stop
    D4xx Driver->>Hardware: Stop and cleanup stream
    Hardware-->>D4xx Driver: Stream stopped
    D4xx Driver-->>V4L2: Notify stream stopped
    V4L2-->>User: Stream closed

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References

• kernel/realsense/d4xx.c
• Device tree overlays in hardware/realsense/
• V4L2 API documentation

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Feedback Requested:
Please specify any missing details, edge cases, or integration points that should be covered in the documentation.