drm/bridge: lt8912b: fix incorrect handling of of_* return values

A static analysis shows several issues in the driver code at
probing time.

DT parsing errors were bad handled and could lead to bugs:
  - Bad error detection;
  - Bad release of resources

Fixes: 30e2ae943c26 ("drm/bridge: Introduce LT8912B DSI to HDMI bridge")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Suggested-by: Dan Carpenter  <dan.carpenter@oracle.com>
Signed-off-by: Adrien Grassein <adrien.grassein@gmail.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210415183639.1487-1-rdunlap@infradead.org
Signed-off-by: Robert Foss <robert.foss@linaro.org>

diff --git a/drivers/gpu/drm/bridge/lontium-lt8912b.c b/drivers/gpu/drm/bridge/lontium-lt8912b.c
index 6149161..55d8aa2 100644 (file)
--- a/drivers/gpu/drm/bridge/lontium-lt8912b.c
+++ b/drivers/gpu/drm/bridge/lontium-lt8912b.c
@@ -621,7 +621,8 @@ static int lt8912_parse_dt(struct lt8912 *lt)
 {
        struct gpio_desc *gp_reset;
        struct device *dev = lt->dev;
-       int ret = 0;
+       int ret;
+       int data_lanes;
        struct device_node *port_node;
        struct device_node *endpoint;
 
@@ -635,19 +636,21 @@ static int lt8912_parse_dt(struct lt8912 *lt)
        lt->gp_reset = gp_reset;
 
        endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
-       if (IS_ERR(endpoint)) {
-               ret = PTR_ERR(endpoint);
-               goto end;
-       }
+       if (!endpoint)
+               return -ENODEV;
 
-       lt->data_lanes = of_property_count_u32_elems(endpoint, "data-lanes");
+       data_lanes = of_property_count_u32_elems(endpoint, "data-lanes");
        of_node_put(endpoint);
+       if (data_lanes < 0) {
+               dev_err(lt->dev, "%s: Bad data-lanes property\n", __func__);
+               return data_lanes;
+       }
+       lt->data_lanes = data_lanes;
 
        lt->host_node = of_graph_get_remote_node(dev->of_node, 0, -1);
        if (!lt->host_node) {
                dev_err(lt->dev, "%s: Failed to get remote port\n", __func__);
-               ret = -ENODEV;
-               goto end;
+               return -ENODEV;
        }
 
        port_node = of_graph_get_remote_node(dev->of_node, 1, -1);
@@ -658,24 +661,23 @@ static int lt8912_parse_dt(struct lt8912 *lt)
        }
 
        lt->hdmi_port = of_drm_find_bridge(port_node);
-       if (IS_ERR(lt->hdmi_port)) {
+       if (!lt->hdmi_port) {
                dev_err(lt->dev, "%s: Failed to get hdmi port\n", __func__);
-               ret = PTR_ERR(lt->hdmi_port);
-               of_node_put(lt->host_node);
-               goto end;
+               ret = -ENODEV;
+               goto err_free_host_node;
        }
 
        if (!of_device_is_compatible(port_node, "hdmi-connector")) {
                dev_err(lt->dev, "%s: Failed to get hdmi port\n", __func__);
                ret = -EINVAL;
+               goto err_free_host_node;
        }
 
        of_node_put(port_node);
-
-end:
-       return ret;
+       return 0;
 
 err_free_host_node:
+       of_node_put(port_node);
        of_node_put(lt->host_node);
        return ret;
 }