[PATCH v6 05/26] drm/debugfs: add top-level 'bridges' file showing all added bridges

Luca Ceresoli
2025-02-06T18:14:51Z

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.

Note: this change requires exporting bridge_list and the mutex protecting
it.

Also add a comment about bridge_lock to make checkpatch happy.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

---

This patch was added in v6.
---
drivers/gpu/drm/drm_bridge.c | 5 +--
drivers/gpu/drm/drm_debugfs.c | 70 +++++++++++++++++++++++++++++-------------
drivers/gpu/drm/drm_drv.c | 1 +
drivers/gpu/drm/drm_internal.h | 9 ++++++
4 files changed, 61 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 241a384ebce39b4a3db58c208af27960904fc662..87cebec2de806781cee22da54d666eee9bde3648 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -195,8 +195,9 @@
* driver.
*/

-static DEFINE_MUTEX(bridge_lock);
-static LIST_HEAD(bridge_list);
+/* Protect bridge_list */
+DEFINE_MUTEX(bridge_lock);
+LIST_HEAD(bridge_list);

/**
* drm_bridge_add - add the given bridge to the global bridge list
diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
index 6b2178864c7ee12db9aa1f562e106b2f604439f8..7424d5237e7615d63de6bba572ee6050da6709d0 100644
--- a/drivers/gpu/drm/drm_debugfs.c
+++ b/drivers/gpu/drm/drm_debugfs.c
@@ -740,6 +740,30 @@ void drm_debugfs_crtc_remove(struct drm_crtc *crtc)
crtc->debugfs_entry = NULL;
}

+static void bridge_print(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 bridges_show(struct seq_file *m, void *data)
{
struct drm_encoder *encoder = m->private;
@@ -747,28 +771,8 @@ static int 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)
+ bridge_print(&p, bridge, idx++);

return 0;
}
@@ -802,3 +806,25 @@ void drm_debugfs_encoder_remove(struct drm_encoder *encoder)
debugfs_remove_recursive(encoder->debugfs_entry);
encoder->debugfs_entry = NULL;
}
+
+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)
+ bridge_print(&p, bridge, idx++);
+
+ mutex_unlock(&bridge_lock);
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(allbridges);
+
+void drm_debugfs_global_add(struct dentry *root)
+{
+ debugfs_create_file("bridges", 0444, root, NULL, &allbridges_fops);
+}
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 3cf440eee8a2ab3de134d925db8f1d2ce68062b7..9b6d7bd16ba409b6a9155a9fecbec6bfdd5ea0c2 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -1120,6 +1120,7 @@ static int __init drm_core_init(void)
}

drm_debugfs_root = debugfs_create_dir("dri", NULL);
+ drm_debugfs_global_add(drm_debugfs_root);

ret = register_chrdev(DRM_MAJOR, "drm", &drm_stub_fops);
if (ret < 0)
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index b2b6a8e49dda46f1cb3b048ef7b28356dd3aaa4e..b6e875d4b25faae6bb0bb952c3c12bd4819698ec 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -48,6 +48,10 @@ struct drm_prime_file_private;
struct drm_printer;
struct drm_vblank_crtc;

+// for drm_debugfs.c
+extern struct mutex bridge_lock;
+extern struct list_head bridge_list;
+
/* drm_client_event.c */
#if defined(CONFIG_DRM_CLIENT)
void drm_client_debugfs_init(struct drm_device *dev);
@@ -196,6 +200,7 @@ void drm_debugfs_crtc_remove(struct drm_crtc *crtc);
void drm_debugfs_crtc_crc_add(struct drm_crtc *crtc);
void drm_debugfs_encoder_add(struct drm_encoder *encoder);
void drm_debugfs_encoder_remove(struct drm_encoder *encoder);
+void drm_debugfs_global_add(struct dentry *drm_debugfs_root);
#else
static inline void drm_debugfs_dev_fini(struct drm_device *dev)
{
@@ -241,6 +246,10 @@ static inline void drm_debugfs_encoder_remove(struct drm_encoder *encoder)
{
}

+static inline void drm_debugfs_global_add(struct dentry *drm_debugfs_root)
+{
+}
+
#endif

drm_ioctl_t drm_version;

--
2.34.1