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

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

Patch Review

**The bug (confirmed in tree):** In the current code at line 1476-1479 of `rzg2l_mipi_dsi.c`:

```c
dsi->dcs_buf_virt = dma_alloc_coherent(dsi->host.dev, RZG2L_DCS_BUF_SIZE,
                                       &dsi->dcs_buf_phys, GFP_KERNEL);
if (!dsi->dcs_buf_virt)
    return -ENOMEM;
```

This bare `return -ENOMEM` leaks two resources:
1. The `mipi_dsi_host_register` at line 1472 is never unregistered.
2. The `pm_runtime_enable` at line 1446 is never disabled.

**The fix is correct and clean:**

1. **`dma_alloc_coherent` → `dmam_alloc_coherent`**: The managed variant ties the DMA buffer lifetime to the device via devres, so no explicit free is needed. This eliminates the `dma_free_coherent` call in `rzg2l_mipi_dsi_remove`, which is correct.

2. **Moving allocation before `platform_set_drvdata` / `pm_runtime_enable`**: At this point in probe, only `devm_`-managed resources (clocks, resets, ioremap) have been acquired. A plain `return -ENOMEM` is safe here — all prior allocations are device-managed and will be cleaned up automatically. The DMA buffer isn't used until actual DSI host transfers, so early allocation is fine.

3. **Device parameter change**: The original used `dsi->host.dev`, the new code uses `dsi->dev`. This is correct because `dsi->host.dev` hasn't been assigned yet at the new call site, and they are set to the same value anyway (line 1470: `dsi->host.dev = dsi->dev`).

**Minor observations (not blocking):**

- The commit message could be slightly more explicit about *what* was leaking (host registration + pm_runtime), but "unwind correctly" is adequate for a Fixes patch.

- The ordering in `remove` now has `mipi_dsi_host_unregister` first and `pm_runtime_disable` second, with the DMA free handled by devres (which runs after `remove` returns). This ordering is correct — devres cleanup happens during device unbind after the driver's remove callback.

**No issues found. Patch is ready.**

Reviewed-by: Dave Airlie <airlied@gmail.com>

---
Generated by Claude Code Patch Reviewer