Claude review: drm/panel: Enable DSC for Visionox VTDR6130 panel

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

Patch Review

**Author:** Jun Nie, signed-off by Neil Armstrong.

This patch adds structured DSC configuration and sends the PPS via the standard MIPI DCS Picture Parameter Set command.

**DSC configuration (probe):**
```c
+	ctx->dsc.dsc_version_major = 0x1;
+	ctx->dsc.dsc_version_minor = 0x2;
+	ctx->dsc.slice_height = 40;
+	ctx->dsc.slice_width = 540;
+	ctx->dsc.slice_count = 2;
+	ctx->dsc.bits_per_component = 8;
+	ctx->dsc.bits_per_pixel = 8 << 4;
+	ctx->dsc.block_pred_enable = true;
+
+	dsi->dsc = &ctx->dsc;
```

These parameters are consistent with the existing hardcoded PPS blob in the 0x70 vendor register (which decodes to: DSC 1.2, pic_height=2400, pic_width=1080, slice_height=40, slice_width=540). The `bits_per_pixel = 8 << 4` (128, i.e. 8.0 bpp with 4 fractional bits) matches the pattern used across all other panel drivers. The remaining DSC parameters (RC model, initial offset, etc.) are populated by the MSM DSI host driver via `dsi_populate_dsc_params()` when it sees `dsi->dsc` is set.

**DSC enable command:**
```c
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x03, 0x01);
```

DCS command 0x03 with value 0x01 enables compression mode on the panel. This is placed correctly at the top of the `_on()` function before other initialization — good.

**PPS transmission:**
```c
+	drm_dsc_pps_payload_pack(&pps, dsi->dsc);
+	mipi_dsi_picture_parameter_set_multi(&dsi_ctx, &pps);
```

Placed after display-on and the 20ms delay. This follows the pattern of other DSC-enabled panel drivers (`panel-visionox-r66451`, `panel-lg-sw43408`, etc.).

**Minor observation (non-blocking):** The existing driver already has a hardcoded PPS-like blob written to vendor register 0x70 (line 64 in the current source). That blob's decoded parameters (DSC 1.2, slice 40x540, 1080x2400) match the new structured DSC config exactly. It would be worth confirming that both the vendor register write and the standard MIPI PPS are needed — but this is common for Qualcomm-reference panels and is almost certainly correct.

**Verdict:** Looks correct. No issues.

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