Claude review: drm/panel: Add panel driver for ChipWealth CH13726A based panels

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

Patch Review

**Issue 1 (Kconfig): Unnecessary DP helper selections**

```c
select DRM_DISPLAY_DP_HELPER
select DRM_DISPLAY_HELPER
```

This is a pure MIPI-DSI panel. The only other panel drivers that `select DRM_DISPLAY_DP_HELPER` are eDP panels (Samsung ATNA33XC20, simple eDP). Comparable MIPI-DSI panel drivers like `DRM_PANEL_BOE_TD4320` select neither of these. Both `select` lines should be removed — the driver doesn't use any display helper or DP helper APIs.

**Issue 2 (const-correctness): `desc` pointer and `thor_bottom_desc` should be const**

The descriptor struct is declared as:

```c
struct ch13726a_desc *desc;
```

and `thor_bottom_desc` is:

```c
static struct ch13726a_desc thor_bottom_desc = {
```

Since `of_device_get_match_data()` returns `const void *`, the current cast discards const:

```c
ctx->desc = (struct ch13726a_desc *)of_device_get_match_data(dev);
```

The field should be `const struct ch13726a_desc *desc`, the variable should be `static const struct ch13726a_desc thor_bottom_desc`, and the cast should be `(const struct ch13726a_desc *)` (or better, dropped entirely since C allows implicit conversion from `const void *` to `const T *`).

**Issue 3 (style): `uint8_t` loop variable in `get_modes`**

```c
for (uint8_t i = 0; i < ctx->desc->num_modes; i++) {
```

Kernel convention is to use `unsigned int` or `int` for loop counters, not fixed-width types. `unsigned int` would match the type of `num_modes`.

**Issue 4 (style): `__typeof(*ctx)` in `devm_drm_panel_alloc`**

```c
ctx = devm_drm_panel_alloc(dev, __typeof(*ctx), panel,
                           &ch13726a_panel_funcs,
                           DRM_MODE_CONNECTOR_DSI);
```

While functionally correct, all other panel drivers pass the struct name directly:

```c
ctx = devm_drm_panel_alloc(dev, struct ch13726a_panel, panel,
                           &ch13726a_panel_funcs,
                           DRM_MODE_CONNECTOR_DSI);
```

**Observation (not a blocker): `of_drm_get_panel_orientation` error path**

```c
ret = of_drm_get_panel_orientation(dev->of_node, &ctx->orientation);
if (ret < 0) {
    dev_err(dev, "%pOF: failed to get orientation %d\n", dev->of_node, ret);
    return ret;
}
```

This could use `dev_err_probe()` for consistency with the other error paths in `probe()`, which would also handle `-EPROBE_DEFER` cleanly:

```c
return dev_err_probe(dev, ret, "Failed to get orientation\n");
```

**Overall for patch 2:** The driver logic itself is solid — the reset sequence, init commands, backlight handling, and multi-rate mode support all look correct. The `mipi_dsi_multi_context` usage is clean, `prepare_prev_first = true` is properly set, and the remove path correctly detaches DSI before removing the panel. The issues above are all minor fixups.

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Generated by Claude Code Patch Reviewer