rs-enum: use media-ctl for Tegra stream type identification

[Nir-Az]

Summary

Replace pixel format heuristics with media-ctl entity name discovery for identifying stream types on Tegra/Jetson.

Problem

The previous approach identified streams by pixel format (Z16=depth, GREY=ir, etc.). This is fragile:

• D585S safety stream uses GREY format → misidentified as IR
• Some IR streams produce color formats → misidentified as color
• Every new format requires script changes

Solution

Parse D4XX entity names from the media controller graph (media-ctl --print-dot). The driver registers entities like D4XX depth, D4XX rgb, D4XX ir, D4XX imu which unambiguously identify the stream type.

Changes

• get_stream_types() — new function replacing identify_dev_type(). Queries media-ctl for D4XX entity names and their DS5 mux port connections. Returns stream types in port order. Handles multi-cam on single deserializer by discovering all I2C addresses on the same bus.
• process_rs_video_devices() — uses get_stream_types() for positional stream type assignment (streaming nodes only, skipping metadata). On Tegra, individual /dev/videoN nodes aren't linked to specific D4XX entities in the media graph — the driver creates them in deterministic DS5 mux port order.
• create_dfu_link() — fixed DFU device matching by I2C address instead of alphabetical ls order, which could swap DFU assignments when bus numbers don't sort lexically (e.g. bus 10 before bus 9).
• IPU6 path is untouched.

Adding new stream types (e.g. safety)

When the driver registers a new entity (e.g. D4XX safety), support requires:

1. scripts/rs-enum.sh: Add the mapping to camera_names (e.g. [safety]=safety), add a counter (safety_dev_counter), and update get_dev_num()/increment_dev_num(). The media-ctl discovery picks up the new entity automatically.
2. src/linux/backend-v4l2.cpp: Add "safety" to the video_sensors vector in get_mipi_rs_enum_nodes() (line 1282) and set the appropriate info.mi value.

Test plan

• Single cam, single deserializer (D457 on Intel Des)
• Multi-cam, single deserializer (2× D457 on FangZhu)
• Multi-cam, multi deserializer (2× D457 on separate FangZhu deserializers)
• DFU links correctly matched by I2C address
• Verify no regression on IPU6 platform (code path untouched)

Test results

D457 on single Intel Des

FangZhu with 2 cam on 1 des
● Both cameras enumerated correctly:

• Camera 0 (9-001a): depth, color, ir, imu + metadata + DFU
• Camera 1 (9-002a): depth, color, ir, imu + metadata + DFU

FungZhu 2 cam each on a different des

[Copilot]

Pull request overview

This PR updates rs-enum.sh’s Tegra/Jetson stream-type identification to prefer media-ctl media-graph entity names (e.g., D4XX depth, D4XX rgb) over pixel-format heuristics, with a fallback to the existing heuristic when media-ctl data is unavailable.

Changes:

• Add discover_stream_types() to infer depth/color/ir/imu ordering from cached media-ctl --print-dot output per I2C address.
• Update Tegra device processing to use discovered stream types when available, falling back to identify_dev_type() otherwise.
• Cache Tegra media-ctl DOT output once to avoid repeated media-ctl invocations per device.

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