drm/exynos: dp: Fix panel and bridge lookup logic

Commit a9fa852886fd ("drm/exynos: dp: add of_graph dt binding support
for panel") made the Exynos DP DT binding more consistent since the OF
graph could be used to lookup either a panel or a bridge device node.

Before that commit, a panel would be looked up using a phandle and a
bridge using the OF graph which made the DT binding not consistent.

But the patch broke the later case since not finding a panel dev node
would cause the driver's to do a probe deferral instead of attempting
to lookup a bridge device node associated with the remote endpoint.

So instead of returning a -EPROBE_DEFER if a panel is not found, check
if there's a bridge and only do a probe deferral if both aren't found.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Tested-by: Michal Suchanek <hramrach@gmail.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

1 files changed, 25 insertions, 30 deletions

diff --git a/drivers/gpu/drm/exynos/exynos_dp_core.c b/drivers/gpu/drm/exynos/exynos_dp_core.c
index b79c316c2ad2..673164b331c8 100644
--- a/drivers/gpu/drm/exynos/exynos_dp_core.c
+++ b/drivers/gpu/drm/exynos/exynos_dp_core.c
@@ -1392,7 +1392,7 @@ static const struct component_ops exynos_dp_ops = {
 static int exynos_dp_probe(struct platform_device *pdev)
 {
         struct device *dev = &pdev->dev;
-        struct device_node *panel_node = NULL, *bridge_node, *endpoint = NULL;
+        struct device_node *np = NULL, *endpoint = NULL;
         struct exynos_dp_device *dp;
         int ret;
 
@@ -1404,41 +1404,36 @@ static int exynos_dp_probe(struct platform_device *pdev)
         platform_set_drvdata(pdev, dp);
 
         /* This is for the backward compatibility. */
-        panel_node = of_parse_phandle(dev->of_node, "panel", 0);
-        if (panel_node) {
-                dp->panel = of_drm_find_panel(panel_node);
-                of_node_put(panel_node);
+        np = of_parse_phandle(dev->of_node, "panel", 0);
+        if (np) {
+                dp->panel = of_drm_find_panel(np);
+                of_node_put(np);
                 if (!dp->panel)
                         return -EPROBE_DEFER;
-        } else {
-                endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
-                if (endpoint) {
-                        panel_node = of_graph_get_remote_port_parent(endpoint);
-                        if (panel_node) {
-                                dp->panel = of_drm_find_panel(panel_node);
-                                of_node_put(panel_node);
-                                if (!dp->panel)
-                                        return -EPROBE_DEFER;
-                        } else {
-                                DRM_ERROR("no port node for panel device.\n");
-                                return -EINVAL;
-                        }
-                }
-        }
-
-        if (endpoint)
                 goto out;
+        }
 
         endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
         if (endpoint) {
-                bridge_node = of_graph_get_remote_port_parent(endpoint);
-                if (bridge_node) {
-                        dp->ptn_bridge = of_drm_find_bridge(bridge_node);
-                        of_node_put(bridge_node);
-                        if (!dp->ptn_bridge)
-                                return -EPROBE_DEFER;
-                } else
-                        return -EPROBE_DEFER;
+                np = of_graph_get_remote_port_parent(endpoint);
+                if (np) {
+                        /* The remote port can be either a panel or a bridge */
+                        dp->panel = of_drm_find_panel(np);
+                        if (!dp->panel) {
+                                dp->ptn_bridge = of_drm_find_bridge(np);
+                                if (!dp->ptn_bridge) {
+                                        of_node_put(np);
+                                        return -EPROBE_DEFER;
+                                }
+                        }
+                        of_node_put(np);
+                } else {
+                        DRM_ERROR("no remote endpoint device node found.\n");
+                        return -EINVAL;
+                }
+        } else {
+                DRM_ERROR("no port endpoint subnode found.\n");
+                return -EINVAL;
         }
 
 out: