drm/debugfs: add top-level 'bridges' file showing all added bridges

The global bridges_list holding all the bridges between drm_bridge_add()
and drm_bridge_remove() cannot be inspected via debugfs. Add a file showing
it.

To avoid code duplication, move the code printing a bridge info to a common
function.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250226-drm-debugfs-show-all-bridges-v8-2-bb511cc49d83@bootlin.com
Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>

3 files changed, 53 insertions, 22 deletions

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 3e23e1f0394d..ea9525ec16b5 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -1301,6 +1301,49 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 EXPORT_SYMBOL(of_drm_find_bridge);
 #endif
 
+static void drm_bridge_debugfs_show_bridge(struct drm_printer *p,
+					   struct drm_bridge *bridge,
+					   unsigned int idx)
+{
+	drm_printf(p, "bridge[%u]: %ps\n", idx, bridge->funcs);
+	drm_printf(p, "\ttype: [%d] %s\n",
+		   bridge->type,
+		   drm_get_connector_type_name(bridge->type));
+
+	if (bridge->of_node)
+		drm_printf(p, "\tOF: %pOFfc\n", bridge->of_node);
+
+	drm_printf(p, "\tops: [0x%x]", bridge->ops);
+	if (bridge->ops & DRM_BRIDGE_OP_DETECT)
+		drm_puts(p, " detect");
+	if (bridge->ops & DRM_BRIDGE_OP_EDID)
+		drm_puts(p, " edid");
+	if (bridge->ops & DRM_BRIDGE_OP_HPD)
+		drm_puts(p, " hpd");
+	if (bridge->ops & DRM_BRIDGE_OP_MODES)
+		drm_puts(p, " modes");
+	if (bridge->ops & DRM_BRIDGE_OP_HDMI)
+		drm_puts(p, " hdmi");
+	drm_puts(p, "\n");
+}
+
+static int allbridges_show(struct seq_file *m, void *data)
+{
+	struct drm_printer p = drm_seq_file_printer(m);
+	struct drm_bridge *bridge;
+	unsigned int idx = 0;
+
+	mutex_lock(&bridge_lock);
+
+	list_for_each_entry(bridge, &bridge_list, list)
+		drm_bridge_debugfs_show_bridge(&p, bridge, idx++);
+
+	mutex_unlock(&bridge_lock);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(allbridges);
+
 static int encoder_bridges_show(struct seq_file *m, void *data)
 {
 	struct drm_encoder *encoder = m->private;
@@ -1308,33 +1351,18 @@ static int encoder_bridges_show(struct seq_file *m, void *data)
 	struct drm_bridge *bridge;
 	unsigned int idx = 0;
 
-	drm_for_each_bridge_in_chain(encoder, bridge) {
-		drm_printf(&p, "bridge[%u]: %ps\n", idx++, bridge->funcs);
-		drm_printf(&p, "\ttype: [%d] %s\n",
-			   bridge->type,
-			   drm_get_connector_type_name(bridge->type));
-
-		if (bridge->of_node)
-			drm_printf(&p, "\tOF: %pOFfc\n", bridge->of_node);
-
-		drm_printf(&p, "\tops: [0x%x]", bridge->ops);
-		if (bridge->ops & DRM_BRIDGE_OP_DETECT)
-			drm_puts(&p, " detect");
-		if (bridge->ops & DRM_BRIDGE_OP_EDID)
-			drm_puts(&p, " edid");
-		if (bridge->ops & DRM_BRIDGE_OP_HPD)
-			drm_puts(&p, " hpd");
-		if (bridge->ops & DRM_BRIDGE_OP_MODES)
-			drm_puts(&p, " modes");
-		if (bridge->ops & DRM_BRIDGE_OP_HDMI)
-			drm_puts(&p, " hdmi");
-		drm_puts(&p, "\n");
-	}
+	drm_for_each_bridge_in_chain(encoder, bridge)
+		drm_bridge_debugfs_show_bridge(&p, bridge, idx++);
 
 	return 0;
 }
 DEFINE_SHOW_ATTRIBUTE(encoder_bridges);
 
+void drm_bridge_debugfs_params(struct dentry *root)
+{
+	debugfs_create_file("bridges", 0444, root, NULL, &allbridges_fops);
+}
+
 void drm_bridge_debugfs_encoder_params(struct dentry *root,
 				       struct drm_encoder *encoder)
 {
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index c9487bc88624..3dc7acd56b1d 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -40,6 +40,7 @@
 #include <linux/xarray.h>
 
 #include <drm/drm_accel.h>
+#include <drm/drm_bridge.h>
 #include <drm/drm_cache.h>
 #include <drm/drm_client_event.h>
 #include <drm/drm_color_mgmt.h>
@@ -1209,6 +1210,7 @@ static int __init drm_core_init(void)
 	}
 
 	drm_debugfs_root = debugfs_create_dir("dri", NULL);
+	drm_bridge_debugfs_params(drm_debugfs_root);
 
 	ret = register_chrdev(DRM_MAJOR, "drm", &drm_stub_fops);
 	if (ret < 0)
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index bacbc5dbf281..b0d86a685a41 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1108,6 +1108,7 @@ static inline struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm,
 }
 #endif
 
+void drm_bridge_debugfs_params(struct dentry *root);
 void drm_bridge_debugfs_encoder_params(struct dentry *root, struct drm_encoder *encoder);
 
 #endif