Claude review: drm: renesas: rz-du: Add support for RZ/T2H SoC

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

Patch Review

The core enablement patch. Adds the device info, feature flag, and DPI output enable handling.

**The feature flag design is clean:**

```c
#define RZG2L_DU_FEATURE_DPIO_OE	BIT(0)

static inline bool rzg2l_du_has(struct rzg2l_du_device *rcdu,
				unsigned int feature)
{
	return rcdu->info->features & feature;
}
```

**The start/stop logic looks correct:**

```c
 static void rzg2l_du_start_stop(struct rzg2l_du_crtc *rcrtc, bool start)
 {
 	struct rzg2l_du_device *rcdu = rcrtc->dev;
+	u32 val = DU_MCR0_DI_EN;
 
-	writel(start ? DU_MCR0_DI_EN : 0, rcdu->mmio + DU_MCR0);
+	if (start && rzg2l_du_has(rcdu, RZG2L_DU_FEATURE_DPIO_OE))
+		val |= DU_MCR0_DPI_EN;
+
+	writel(start ? val : 0, rcdu->mmio + DU_MCR0);
 }
```

When `start` is false, the write is `0` regardless — clearing both DI_EN and DPI_EN. When `start` is true, DPI_EN is conditionally ORed in. This is correct.

**Issue 1 — `val` initialization is misleading when `start` is false:**

`val` is always initialized to `DU_MCR0_DI_EN` even when `start` is false, in which case it's unused (the ternary writes `0`). This is harmless but slightly confusing — a reader might wonder if `val` matters when `start` is false. The logic is correct but could be clearer with a restructure. Very minor.

**Issue 2 — RZ/T2H device info uses `.port = 0` for DPAD0:**

```c
+static const struct rzg2l_du_device_info rzg2l_du_r9a09g077_info = {
+	.channels_mask = BIT(0),
+	.routes = {
+		[RZG2L_DU_OUTPUT_DPAD0] = {
+			.possible_outputs = BIT(0),
+			.port = 0,
+		},
+	},
```

This matches the DT binding where T2H uses a bare `port` instead of `ports/port@0`. But the driver's `rzg2l_du_modeset_init()` function uses `of_graph_get_remote_node()` which takes a port number. We should verify that `of_graph_get_remote_node(rcdu->dev->of_node, 0, 0)` works with a bare `port` property (no `ports` container). The OF graph API does support bare `port` nodes — it falls through from looking for `ports/port@N` to looking for `port` when there's only one port. So this should work, but it's worth a quick sanity check.

**Issue 3 — The `features` field doc appears in patch 4 but struct changes span patches 3 and 4:**

In patch 3, `mode_clock_min` and `mode_clock_max` are added to the struct with documentation. In patch 4, `features` is added. The kernel-doc comment for the struct is updated incrementally across both patches, which is fine.

**Overall the patch is clean.** The feature flag mechanism and conditional DPI_EN assertion are well done.

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Generated by Claude Code Patch Reviewer