Claude review: drm: renesas: rz-du: mipi_dsi: Fix return path on error

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

Overall Series Review

Subject: drm: renesas: rz-du: mipi_dsi: Fix return path on error
Author: Chris Brandt <chris.brandt@renesas.com>
Patches: 1
Reviewed: 2026-05-05T09:27:22.127017

---

This is a single-patch series (v3) that fixes an error-handling bug in the Renesas RZ MIPI DSI probe path. The original code had two problems:

1. **Missing error unwind**: The `dma_alloc_coherent()` call was placed after `mipi_dsi_host_register()`, and on failure it did `return -ENOMEM` directly — skipping the `err_pm_disable` cleanup label, which means `pm_runtime_disable()` and `mipi_dsi_host_unregister()` were never called on that error path.

2. **Leaked DMA allocation**: Since plain `dma_alloc_coherent()` was used, any other error path that went through the `err_phy` / `err_pm_disable` labels would also leak the DMA buffer (though in practice this was unreachable since the alloc came last).

The fix is clean and correct: switch to `dmam_alloc_coherent()` (device-managed) and move it earlier in the probe function — before `platform_set_drvdata()` and `pm_runtime_enable()` — so that on failure, a simple `return -ENOMEM` is sufficient (no cleanup needed at that point), and the buffer is automatically freed on device removal. The corresponding `dma_free_coherent()` in `remove()` is correctly dropped.

The patch has a `Fixes:` tag, a `Reviewed-by` from Biju Das, is on its third revision addressing prior review feedback, and the changelog is well documented. **Recommend: Accept.**

---
Generated by Claude Code Patch Reviewer