Claude review: drm/amd/display: use DisplayID panel type in dm_set_panel_type

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

Patch Review

**Purpose:** Wires up `did_panel_type` into amdgpu_dm's detection priority chain.

**Priority placement:** The new block is inserted correctly — after the VSDB and DPCD checks, before the Samsung luminance heuristic:

```c
+	/* If VSDB and DPCD didn't determine panel type, check DID */
+	if (link->panel_type == PANEL_TYPE_NONE) {
+		if (display_info->did_panel_type == DRM_MODE_PANEL_TYPE_LCD)
+			link->panel_type = PANEL_TYPE_LCD;
+		else if (display_info->did_panel_type == DRM_MODE_PANEL_TYPE_OLED)
+			link->panel_type = PANEL_TYPE_OLED;
+	}
```

**Effectiveness concern:** The existing end-of-function code only exposes OLED to userspace:

```c
	if (link->panel_type == PANEL_TYPE_OLED)
		drm_object_property_set_value(..., DRM_MODE_PANEL_TYPE_OLED);
	else
		drm_object_property_set_value(..., DRM_MODE_PANEL_TYPE_UNKNOWN);
```

So `PANEL_TYPE_LCD` detected via DisplayID would internally set `link->panel_type = PANEL_TYPE_LCD` (which is `1` in `dc_types.h`), but the userspace property would still read "unknown". Currently no DC code checks `panel_type == PANEL_TYPE_LCD` anywhere, so this detection has no observable effect unless there are downstream consumers added later. This may be intentional (laying groundwork), but it should be documented or the property-setting code should be updated to also handle LCD.

**Cross-domain constant mixing:** The code mixes UAPI constants (`DRM_MODE_PANEL_TYPE_LCD`) with internal DC constants (`PANEL_TYPE_LCD`). This works because they're independent enums, but it's somewhat unusual to compare a `drm_display_info` field set with UAPI values against those UAPI values and then assign internal DC enum values. This is fine functionally but worth noting for maintainability — a mapping helper could improve clarity.

**Overall for Patch 3:** The TODO removal is welcome and the fallback insertion point is correct. The main gap is that LCD detection currently has no visible effect.

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Generated by Claude Code Patch Reviewer