Claude review: drm/ttm: Support 52-bit PAs in ttm_place

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

Overall Series Review

Subject: drm/ttm: Support 52-bit PAs in ttm_place
Author: Felix Kuehling <felix.kuehling@amd.com>
Patches: 4
Reviewed: 2026-05-16T12:38:59.764368

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This is a single patch that widens `fpfn` and `lpfn` in `struct ttm_place` from `unsigned` (32-bit) to `unsigned long` to support physical addresses beyond 44 bits (32-bit page numbers × 4KB pages). The motivation is sound — 32-bit page frame numbers limit addressing to 16 TiB, which is increasingly insufficient.

However, **this patch is already superseded by work in drm-next**. The current drm-next tree already has these fields as `uint64_t`:

```c
struct ttm_place {
	uint64_t	fpfn;
	uint64_t	lpfn;
	uint32_t	mem_type;
	uint32_t	flags;
};
```

The `uint64_t` approach in drm-next is **strictly better** than the `unsigned long` proposed here, because `unsigned long` is only 32-bit on 32-bit platforms, providing no improvement there, while `uint64_t` is unconditionally 64-bit.

**Recommendation: NAK — this change has already landed in drm-next with a superior type choice (`uint64_t` vs `unsigned long`).**

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