Claude review: drm/amd/display: Replace use of system_wq with system_percpu_wq

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

Patch Review

**Correctness concern — per-CPU workqueue may not be appropriate here:**

Both work items modified in this patch do not have per-CPU affinity requirements:

1. **`schedule_dc_vmin_vmax`** (line 575): The work handler `dm_handle_vmin_vmax_update` immediately takes `adev->dm.dc_lock` (a mutex) and calls `dc_stream_adjust_vmin_vmax`. There is no reason this work needs to run on the CPU that queued it — it operates on device-global state protected by a mutex.

2. **`handle_hpd_irq_helper`** (line 4145): The delayed work for HDMI HPD debouncing performs connector hotplug detection. Again, there is no CPU-affinity requirement — this is device-level connector handling.

`system_percpu_wq` is a per-CPU workqueue (`WQ_PERCPU`), meaning work items will execute on the same CPU that queued them. For IRQ handler offloading (the vmin/vmax case is called from `dm_vupdate_high_irq`), pinning work to the interrupt-servicing CPU might cause unnecessary load imbalance, especially since the work immediately contends on a global mutex anyway.

**The more appropriate replacement** for these use cases would likely be `system_dfl_wq` (the replacement for `system_unbound_wq`), which allows the scheduler to place the work optimally, or simply staying with the current `system_wq` until the migration plan for non-CPU-affine users is clarified.

**Suggestion:** Confirm with the workqueue maintainers (Tejun Heo) whether `system_percpu_wq` is indeed the correct target for work items that have no per-CPU affinity requirement. The referenced refactoring thread suggests `system_wq -> system_percpu_wq` as a blanket mapping, but for work items that take global mutexes and operate on shared device state, `system_dfl_wq` may be more appropriate.

**Code changes themselves are mechanically correct** — the API signatures for `queue_work()` and `mod_delayed_work()` accept any `struct workqueue_struct *`, so the substitution compiles and functions correctly regardless of which workqueue is chosen.

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Generated by Claude Code Patch Reviewer