Claude review: drm/ast: Add timeouts to AHB/SCU polling loops to prevent soft lockups

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

Overall Series Review

Subject: drm/ast: Add timeouts to AHB/SCU polling loops to prevent soft lockups
Author: <w15303746062@163.com>
Patches: 1
Reviewed: 2026-05-16T12:09:52.113846

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**NAK — Patch is against a stale tree and the underlying code has been refactored away.**

This single patch targets two files (`ast_post.c` and `ast_2500.c`) to add timeouts to polling loops in `__ast_mindwm`, `__ast_moutdwm`, and `ast_2500_patch_ahb`. However, the code has been substantially refactored in the current drm-next tree:

1. **`__ast_mindwm` and `__ast_moutdwm` no longer contain polling loops.** They were moved from `ast_post.c` to `ast_drv.c` and rewritten to use `__ast_selseg` / `__ast_rdseg32` / `__ast_wrseg32` helpers. The old segment-selection polling loop (`do { data = __ast_read32(...) & 0xffff0000; } while (data != ...)`) now lives in `__ast_selseg()` at `ast_drv.c:63-67`.

2. **`ast_2500_patch_ahb` was also refactored** — it now uses symbolic register names (`AST_REG_SCU000`, `AST_REG_SCU000_PROTECTION_KEY`, etc.) instead of raw hex addresses (`0x1e6e2000`, `0x1688A8A8`). The patch's context lines reference the old raw-hex code and won't apply.

3. **There is also `ast_moutdwm_poll`** at `ast_drv.c:105-115` which has yet another unbounded polling loop using `cpu_relax()` — the patch doesn't address this one.

The underlying concern (unbounded polling loops that can cause soft lockups) remains valid, but a new patch would need to target the current code structure, addressing loops in:
- `__ast_selseg()` (`ast_drv.c:63-67`)
- `ast_moutdwm_poll()` (`ast_drv.c:112-114`)
- `ast_2500_patch_ahb()` (`ast_2500.c:136-139`)

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