Claude review: drm/bridge: imx8mp-hdmi-tx: add an hdmi-connector when missing using a DT overlay at boot time

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

This is the most complex and controversial patch. The approach is reasonable and has precedent (`drm/tilcdc`).

**Observations on the C code (`imx8mp-hdmi-tx-connector-fixup.c`):**

1. The hardcoded path `/soc@0/bus@32c00000/hdmi@32fd8000` is fragile — it only works for i.MX8MP and assumes a specific DT structure. However, since the Kconfig already ties this to `DRM_IMX8MP_DW_HDMI_BRIDGE`, this is acceptable.

2. The `hdmi_conn` lookup after overlay application seems unnecessary:
   ```c
   hdmi_conn = of_find_node_by_name(NULL, "fixup-hdmi-connector");
   if (!hdmi_conn) {
       err = -ENODEV;
       goto overlay_remove;
   }
   ```
   If the overlay applied successfully, the node should always exist. This looks like a sanity check, but the `hdmi_conn` variable is declared with `__free(device_node)` and then never used beyond the NULL check. This is fine for validation but could use a comment explaining it's a sanity check.

3. The overlay is never removed on module exit / cleanup (no `module_exit`). Since this is `bool` (not tristate) in Kconfig, there's no module unload path, which is fine. But this means the overlay ID `ovcs_id` is a dead store if the function succeeds — not a real issue but worth noting.

4. Using `subsys_initcall` is the right level to ensure this runs before device probing.

**On the DT overlay (`imx8mp-hdmi-tx-connector-fixup.dtso`):**
The overlay looks correct. It adds the `fixup-hdmi-connector` node at the root and links it bidirectionally to `port@1` of the HDMI TX.

**One-line change in `imx8mp-hdmi-tx.c`:**
```c
plat_data->output_port = 1;
```
This enables the "case B" mode in dw-hdmi. This is correct and is the key change that makes the HDMI pipeline work with `DRM_BRIDGE_ATTACH_NO_CONNECTOR`. However, this change also affects the non-`DRM_BRIDGE_ATTACH_NO_CONNECTOR` path — in the current tree, dw-hdmi will now call `dw_hdmi_parse_dt()` at probe time, which will look for a remote on port@1. For boards that already have an hdmi-connector in DT this is fine, but for boards that don't (and don't have the fixup), `dw_hdmi_parse_dt()` would return `-ENODEV` and **probe would fail**. This is only safe because patch 6 removes `dw_hdmi_parse_dt()` entirely — so patches 6 and 7 must be applied together (bisectability concern if the `output_port = 1` line were in a separate patch from patch 6, but since patch 6 comes first, bisecting should be fine).

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