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

imx8qxp_pxl2dpi_get_available_ep_from_port() returns ERR_PTR()
on errors. imx8qxp_pxl2dpi_find_next_bridge() stores its return
value in a __free(device_node) variable before checking IS_ERR().
When the function returns on the error path, the cleanup action calls
of_node_put() on the ERR_PTR() value.

Do not let a device_node cleanup variable hold error pointers. Change
imx8qxp_pxl2dpi_get_available_ep_from_port() to return an int and pass
the endpoint node through an output argument. Initialize the output
argument to NULL so callers hold either NULL on error paths or a valid
device_node pointer on successful path.

Fixes: ceea3f7806a10 ("drm/bridge: imx8qxp-pxl2dpi: simplify put of device_node pointers")
Cc: stable@vger.kernel.org
Reviewed-by: Liu Ying <victor.liu@nxp.com>
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
Link: https://patch.msgid.link/20260507100604.667731-1-lgs201920130244@gmail.com
Signed-off-by: Liu Ying <victor.liu@nxp.com>

diff --git a/drivers/gpu/drm/bridge/imx/imx8qxp-pxl2dpi.c b/drivers/gpu/drm/bridge/imx/imx8qxp-pxl2dpi.c
index 441fd32dc91c7a3e61e1f19a33726aca4349d66c..d64e328bf542f39005fe157f2f3329e8fa1c4b0e 100644 (file)
--- a/drivers/gpu/drm/bridge/imx/imx8qxp-pxl2dpi.c
+++ b/drivers/gpu/drm/bridge/imx/imx8qxp-pxl2dpi.c
@@ -222,52 +222,58 @@ static const struct drm_bridge_funcs imx8qxp_pxl2dpi_bridge_funcs = {
                        imx8qxp_pxl2dpi_bridge_atomic_get_output_bus_fmts,
 };
 
-static struct device_node *
+static int
 imx8qxp_pxl2dpi_get_available_ep_from_port(struct imx8qxp_pxl2dpi *p2d,
-                                          u32 port_id)
+                                          u32 port_id,
+                                          struct device_node **ep)
 {
-       struct device_node *port, *ep;
+       struct device_node *port;
+       int ret = 0;
        int ep_cnt;
 
+       *ep = NULL;
+
        port = of_graph_get_port_by_id(p2d->dev->of_node, port_id);
        if (!port) {
                DRM_DEV_ERROR(p2d->dev, "failed to get port@%u\n", port_id);
-               return ERR_PTR(-ENODEV);
+               return -ENODEV;
        }
 
        ep_cnt = of_get_available_child_count(port);
        if (ep_cnt == 0) {
                DRM_DEV_ERROR(p2d->dev, "no available endpoints of port@%u\n",
                              port_id);
-               ep = ERR_PTR(-ENODEV);
+               ret = -ENODEV;
                goto out;
        } else if (ep_cnt > 1) {
                DRM_DEV_ERROR(p2d->dev,
                              "invalid available endpoints of port@%u\n",
                              port_id);
-               ep = ERR_PTR(-EINVAL);
+               ret = -EINVAL;
                goto out;
        }
 
-       ep = of_get_next_available_child(port, NULL);
-       if (!ep) {
+       *ep = of_get_next_available_child(port, NULL);
+       if (!*ep) {
                DRM_DEV_ERROR(p2d->dev,
                              "failed to get available endpoint of port@%u\n",
                              port_id);
-               ep = ERR_PTR(-ENODEV);
+               ret = -ENODEV;
                goto out;
        }
 out:
        of_node_put(port);
-       return ep;
+       return ret;
 }
 
 static int imx8qxp_pxl2dpi_find_next_bridge(struct imx8qxp_pxl2dpi *p2d)
 {
-       struct device_node *ep __free(device_node) =
-               imx8qxp_pxl2dpi_get_available_ep_from_port(p2d, 1);
-       if (IS_ERR(ep))
-               return PTR_ERR(ep);
+       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;
 
        struct device_node *remote __free(device_node) = of_graph_get_remote_port_parent(ep);
        if (!remote || !of_device_is_available(remote)) {
@@ -291,9 +297,9 @@ static int imx8qxp_pxl2dpi_set_pixel_link_sel(struct imx8qxp_pxl2dpi *p2d)
        struct of_endpoint endpoint;
        int ret;
 
-       ep = imx8qxp_pxl2dpi_get_available_ep_from_port(p2d, 0);
-       if (IS_ERR(ep))
-               return PTR_ERR(ep);
+       ret = imx8qxp_pxl2dpi_get_available_ep_from_port(p2d, 0, &ep);
+       if (ret)
+               return ret;
 
        ret = of_graph_parse_endpoint(ep, &endpoint);
        if (ret) {