Claude review: nouveau/gsp/rpc: Document RPC function return value contracts

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

Patch Review

This patch adds kernel-doc comments documenting return value semantics. The analysis is mostly correct, but there is a **major placement bug**:

The doc comment for `r535_gsp_rpc_get` is placed before `r535_gsp_rpc_done()`, not before `r535_gsp_rpc_get()`:

```c
+/**
+ * r535_gsp_rpc_get - Allocate and initialize an RPC message
+ * @gsp: GSP device
+ * @fn: RPC function number
+ * @payload_size: Size of the payload
+ *
+ * Return: Pointer to RPC payload data on success, or ERR_PTR() on error.
+ *         Never returns NULL.
+ */
 static void
 r535_gsp_rpc_done(struct nvkm_gsp *gsp, void *repv)
```

In the source, `r535_gsp_rpc_done()` (line 604) comes before `r535_gsp_rpc_get()` (line 612). The doc comment is attached to the wrong function. The kernel-doc tooling would associate this `@gsp`, `@fn`, `@payload_size` documentation with `r535_gsp_rpc_done`, which only takes `(gsp, repv)` — a parameter mismatch that would produce kernel-doc warnings.

Minor: these are all `static` functions, so kernel-doc comments are somewhat unconventional here — inline `/* */` comments noting the return contract would suffice and be less maintenance burden.

---
Generated by Claude Code Patch Reviewer