[bug report] drm/bridge: Introduce LT8912B DSI to HDMI bridge

[Dan Carpenter]

Hello Adrien Grassein,

The patch 30e2ae943c26: "drm/bridge: Introduce LT8912B DSI to HDMI
bridge" from Mar 26, 2021, leads to the following static checker
warning:

	drivers/gpu/drm/bridge/lontium-lt8912b.c:638 lt8912_parse_dt()
	warn: 'endpoint' isn't an ERR_PTR

drivers/gpu/drm/bridge/lontium-lt8912b.c
   620  static int lt8912_parse_dt(struct lt8912 *lt)
   621  {
   622          struct gpio_desc *gp_reset;
   623          struct device *dev = lt->dev;
   624          int ret = 0;
   625          struct device_node *port_node;
   626          struct device_node *endpoint;
   627  
   628          gp_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
   629          if (IS_ERR(gp_reset)) {
   630                  ret = PTR_ERR(gp_reset);
   631                  if (ret != -EPROBE_DEFER)
   632                          dev_err(dev, "Failed to get reset gpio: %d\n", ret);
   633                  return ret;
   634          }
   635          lt->gp_reset = gp_reset;
   636  
   637          endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
   638          if (IS_ERR(endpoint)) {

Endpoint isn't an error pointer.  You could just delete this check if
you wanted and check of_property_count_u32_elems() for errors.

   639                  ret = PTR_ERR(endpoint);
   640                  goto end;

goto end is a do nothing goto.  Genereally direct returns are more
readable have fewer bugs (based on ten years of reviewing static
analysis warnings).

   641          }
   642  
   643          lt->data_lanes = of_property_count_u32_elems(endpoint, "data-lanes");

Either way, it's probably a good idea to check if
of_property_count_u32_elems() fails.

   644          of_node_put(endpoint);
   645  
   646          lt->host_node = of_graph_get_remote_node(dev->of_node, 0, -1);
   647          if (!lt->host_node) {
   648                  dev_err(lt->dev, "%s: Failed to get remote port\n", __func__);
   649                  ret = -ENODEV;
   650                  goto end;
   651          }
   652  
   653          port_node = of_graph_get_remote_node(dev->of_node, 1, -1);
   654          if (!port_node) {
   655                  dev_err(lt->dev, "%s: Failed to get connector port\n", __func__);
   656                  ret = -ENODEV;
   657                  goto err_free_host_node;
   658          }
   659  
   660          lt->hdmi_port = of_drm_find_bridge(port_node);
   661          if (IS_ERR(lt->hdmi_port)) {
   662                  dev_err(lt->dev, "%s: Failed to get hdmi port\n", __func__);
   663                  ret = PTR_ERR(lt->hdmi_port);
   664                  of_node_put(lt->host_node);
   665                  goto end;

This should call of_node_put(port_node); then goto err_free_host_node;

   666          }
   667  
   668          if (!of_device_is_compatible(port_node, "hdmi-connector")) {
   669                  dev_err(lt->dev, "%s: Failed to get hdmi port\n", __func__);
   670                  ret = -EINVAL;

This should call of_node_put(port_node); then goto err_free_host_node;
as well.

   671          }
   672  
   673          of_node_put(port_node);
   674  
   675  end:
   676          return ret;
   677  
   678  err_free_host_node:
   679          of_node_put(lt->host_node);
   680          return ret;
   681  }

regards,
dan carpenter