Claude review: drm/i915: replace select with dependency for visible DEBUG_OBJECTS

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

Patch Review

**The change:**
```diff
-	select DEBUG_OBJECTS
+	depends on DEBUG_OBJECTS
```

**Issue 1 (functional regression — blocker):** `DRM_I915_DEBUG` (Kconfig.debug:36) contains:

```
select DRM_I915_SW_FENCE_DEBUG_OBJECTS
```

With the old code, enabling `DRM_I915_DEBUG` would pull in `DRM_I915_SW_FENCE_DEBUG_OBJECTS`, which in turn pulled in `DEBUG_OBJECTS` via `select`. The full debug chain worked automatically.

After this patch, `DRM_I915_SW_FENCE_DEBUG_OBJECTS` now `depends on DEBUG_OBJECTS`. When Kconfig processes the `select DRM_I915_SW_FENCE_DEBUG_OBJECTS` from `DRM_I915_DEBUG`, if `DEBUG_OBJECTS` is not already enabled, the `select` is silently ignored because the dependency is unsatisfied. This means a developer enabling `DRM_I915_DEBUG` (the umbrella debug option) will silently lose sw_fence debug object tracking — the opposite of the expected behavior.

To fix this properly, the author needs to also add `select DEBUG_OBJECTS` (or `depends on DEBUG_OBJECTS`) to `DRM_I915_DEBUG` itself, so that the dependency is satisfied before `DRM_I915_SW_FENCE_DEBUG_OBJECTS` is selected. For example:

```
config DRM_I915_DEBUG
    ...
    select DEBUG_OBJECTS
    select DRM_I915_SW_FENCE_DEBUG_OBJECTS
```

Or alternatively, `DRM_I915_DEBUG` could switch from `select DRM_I915_SW_FENCE_DEBUG_OBJECTS` to `select DRM_I915_SW_FENCE_DEBUG_OBJECTS if DEBUG_OBJECTS`, making the dependency chain explicit.

**Issue 2 (minor — usability):** `DEBUG_OBJECTS` itself has dependencies (`depends on PREEMPT_COUNT || !DEFERRED_STRUCT_PAGE_INIT` and `depends on DEBUG_KERNEL`). With the old `select`, these were irrelevant for the i915 path — the symbol was force-enabled. Now users must ensure `DEBUG_KERNEL` (and potentially `PREEMPT_COUNT`) are enabled for `DRM_I915_SW_FENCE_DEBUG_OBJECTS` to even appear in menuconfig. This may be intentional (making the dependency explicit), but it changes the usability for developers who just want fence debugging without the full `DRM_I915_DEBUG` umbrella.

**Nit:** The commit message says "Other config options use 'depends on' for DEBUG_OBJECTS" — this is true, but all those other options (`DEBUG_OBJECTS_SELFTEST`, `DEBUG_OBJECTS_FREE`, etc. in `lib/Kconfig.debug`) are children of the `DEBUG_OBJECTS` menu and are never force-selected by anything. The i915 case is different because of the `select` chain from `DRM_I915_DEBUG`, so the analogy doesn't fully hold.

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Generated by Claude Code Patch Reviewer