Claude review: drm/vblank: timer: Return success status from get_vblank_timeout

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

Patch Review

**Concept:** Good. Propagating failure instead of silently returning `ktime_get()` is the right thing.

**Issue: vmwgfx caller not updated.** `vmw_vkms_get_vblank_timestamp()` at `drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c:245` still calls `drm_crtc_vblank_get_vblank_timeout(crtc, vblank_time)` and ignores the return value, unconditionally returning `true`:

```c
drm_crtc_vblank_get_vblank_timeout(crtc, vblank_time);
return true;
```

After this patch, when the function returns `false`, `vblank_time` is uninitialized/stale, yet vmwgfx will report success to the vblank core. This needs the same treatment as `drm_crtc_vblank_helper_get_vblank_timestamp_from_timer`:

```c
return drm_crtc_vblank_get_vblank_timeout(crtc, vblank_time);
```

**Minor:** The existing `drm_WARN_ON(crtc->dev, !ktime_compare(...))` path in the original code returned `void`, so it was a silent "give up." Now it returns `false`, which is correct behavior, but the `drm_WARN_ON` will print a kernel warning for a condition that may not truly be an error (the timer could have legitimately just expired). Consider whether a `drm_dbg_vbl` is more appropriate here.

---

---
Generated by Claude Code Patch Reviewer