Claude review: drm/bridge: imx8qxp-pxl2dpi: avoid ERR_PTR with device_node cleanup

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

Patch Review

**Bug analysis:** Correct. The existing code at line 267-268 of the current tree:
```c
struct device_node *ep __free(device_node) =
    imx8qxp_pxl2dpi_get_available_ep_from_port(p2d, 1);
```
stores an `ERR_PTR()` in a `__free(device_node)` variable. Since `DEFINE_FREE(device_node, ...)` is defined as:
```c
DEFINE_FREE(device_node, struct device_node *, if (_T) of_node_put(_T))
```
an `ERR_PTR()` passes the `if (_T)` check (it's non-NULL) and `of_node_put()` is called on a bogus error-encoding pointer.

**Fix approach (helper refactoring):** Clean and idiomatic. The function signature change from:
```c
static struct device_node *
imx8qxp_pxl2dpi_get_available_ep_from_port(struct imx8qxp_pxl2dpi *p2d,
                                           u32 port_id)
```
to:
```c
static int
imx8qxp_pxl2dpi_get_available_ep_from_port(struct imx8qxp_pxl2dpi *p2d,
                                           u32 port_id,
                                           struct device_node **ep)
```
is a reasonable pattern. The output parameter `*ep` is initialized to `NULL` at the top, and only set to a valid node on success.

**Helper function internals:** The `port` variable is now also managed with `__free(device_node)`:
```c
struct device_node *port __free(device_node) =
    of_graph_get_port_by_id(p2d->dev->of_node, port_id);
```
This is correct — `of_graph_get_port_by_id()` returns `NULL` on failure (not `ERR_PTR()`), so the cleanup is safe and eliminates the old `goto out` / `of_node_put(port)` pattern.

**Caller `imx8qxp_pxl2dpi_find_next_bridge()`:** Correctly updated:
```c
struct device_node *ep __free(device_node) = NULL;
int ret;

ret = imx8qxp_pxl2dpi_get_available_ep_from_port(p2d, 1, &ep);
if (ret)
    return ret;
```
The `ep` is initialized to `NULL`, so if the function fails (returning a negative error), `ep` remains `NULL` and the `__free(device_node)` cleanup is a safe no-op.

**Caller `imx8qxp_pxl2dpi_set_pixel_link_sel()`:** Also correctly updated. Additionally, this caller now uses `__free(device_node)` for `ep` where it previously used manual `of_node_put()`. The `goto out` / manual cleanup pattern is removed, and the function now returns early on errors:
```c
ret = of_graph_parse_endpoint(ep, &endpoint);
if (ret) {
    DRM_DEV_ERROR(p2d->dev,
                  "failed to parse endpoint of port@0: %d\n", ret);
    return ret;
}

p2d->pl_sel = endpoint.id;
return 0;
```
This is a nice improvement — it makes the second caller consistent with the first and simplifies the control flow.

**Minor nit — Fixes tag format:**
```
Fixes: ceea3f7806a10 ("drm/bridge: imx8qxp-pxl2dpi: ...")
```
The abbreviated SHA `ceea3f7806a10` is 13 hex characters. The kernel convention (`checkpatch.pl`) expects exactly 12. Should be `ceea3f7806a1`. This is cosmetic and wouldn't block acceptance, but is worth mentioning for a clean commit log.

**Overall:** The patch correctly identifies and fixes a real bug, the approach is clean, both callers are properly updated, and the commit message is clear and well-written. Reviewed-by-worthy with the optional Fixes tag nit.

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Generated by Claude Code Patch Reviewer