[PATCH v2 1/2] drm/debugfs: add a "force" file per connector

[Thomas Wood]

Add a file to debugfs for each connector to enable modification of the
"force" connector attribute. This allows connectors to be enabled or
disabled for testing and debugging purposes.

v2: Add stricter value checking and clean up debugfs_entry if file
    creation fails in drm_debugfs_connector_add. (David Herrmann)

Signed-off-by: Thomas Wood <thomas.wood at intel.com>
---
 drivers/gpu/drm/drm_crtc.c    |  17 ++++++-
 drivers/gpu/drm/drm_debugfs.c | 114 ++++++++++++++++++++++++++++++++++++++++++
 include/drm/drmP.h            |  11 ++++
 include/drm/drm_crtc.h        |   2 +
 4 files changed, 143 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 365e2c0..fdb69f7 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -888,6 +888,8 @@ int drm_connector_init(struct drm_device *dev,
 	drm_object_attach_property(&connector->base,
 				      dev->mode_config.dpms_property, 0);
 
+	connector->debugfs_entry = NULL;
+
 out_put:
 	if (ret)
 		drm_mode_object_put(dev, &connector->base);
@@ -938,7 +940,19 @@ EXPORT_SYMBOL(drm_connector_cleanup);
  */
 int drm_connector_register(struct drm_connector *connector)
 {
-	return drm_sysfs_connector_add(connector);
+	int ret;
+
+	ret = drm_sysfs_connector_add(connector);
+	if (ret)
+		return ret;
+
+	ret = drm_debugfs_connector_add(connector);
+	if (ret) {
+		drm_sysfs_connector_remove(connector);
+		return ret;
+	}
+
+	return 0;
 }
 EXPORT_SYMBOL(drm_connector_register);
 
@@ -951,6 +965,7 @@ EXPORT_SYMBOL(drm_connector_register);
 void drm_connector_unregister(struct drm_connector *connector)
 {
 	drm_sysfs_connector_remove(connector);
+	drm_debugfs_connector_remove(connector);
 }
 EXPORT_SYMBOL(drm_connector_unregister);
 
diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
index b4b51d4..8ab3f3e 100644
--- a/drivers/gpu/drm/drm_debugfs.c
+++ b/drivers/gpu/drm/drm_debugfs.c
@@ -237,5 +237,119 @@ int drm_debugfs_cleanup(struct drm_minor *minor)
 	return 0;
 }
 
+static int connector_show(struct seq_file *m, void *data)
+{
+	struct drm_connector *connector = m->private;
+	const char *status;
+
+	switch (connector->force) {
+	case DRM_FORCE_ON:
+		status = "on\n";
+		break;
+
+	case DRM_FORCE_ON_DIGITAL:
+		status = "digital\n";
+		break;
+
+	case DRM_FORCE_OFF:
+		status = "off\n";
+		break;
+
+	case DRM_FORCE_UNSPECIFIED:
+		status = "unspecified\n";
+		break;
+
+	default:
+		return 0;
+	}
+
+	seq_puts(m, status);
+
+	return 0;
+}
+
+static int connector_open(struct inode *inode, struct file *file)
+{
+	struct drm_connector *dev = inode->i_private;
+
+	return single_open(file, connector_show, dev);
+}
+
+static ssize_t connector_write(struct file *file, const char __user *ubuf,
+			       size_t len, loff_t *offp)
+{
+	struct seq_file *m = file->private_data;
+	struct drm_connector *connector = m->private;
+	char buf[12];
+
+	if (len > sizeof(buf) - 1)
+		return -EINVAL;
+
+	if (copy_from_user(buf, ubuf, len))
+		return -EFAULT;
+
+	buf[len] = '\0';
+
+	if (!strcmp(buf, "on"))
+		connector->force = DRM_FORCE_ON;
+	else if (!strcmp(buf, "digital"))
+		connector->force = DRM_FORCE_ON_DIGITAL;
+	else if (!strcmp(buf, "off"))
+		connector->force = DRM_FORCE_OFF;
+	else if (!strcmp(buf, "unspecified"))
+		connector->force = DRM_FORCE_UNSPECIFIED;
+	else
+		return -EINVAL;
+
+	return len;
+}
+
+static const struct file_operations drm_connector_fops = {
+	.owner = THIS_MODULE,
+	.open = connector_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+	.write = connector_write
+};
+
+int drm_debugfs_connector_add(struct drm_connector *connector)
+{
+	struct drm_minor *minor = connector->dev->primary;
+	struct dentry *root, *ent;
+
+	if (!minor->debugfs_root)
+		return -1;
+
+	root = debugfs_create_dir(connector->name, minor->debugfs_root);
+	if (!root)
+		return -ENOMEM;
+
+	connector->debugfs_entry = root;
+
+	/* force */
+	ent = debugfs_create_file("force", S_IRUGO | S_IWUSR, root, connector,
+				  &drm_connector_fops);
+	if (!ent)
+		goto error;
+
+	return 0;
+
+error:
+	debugfs_remove_recursive(connector->debugfs_entry);
+	connector->debugfs_entry = NULL;
+	return -ENOMEM;
+}
+
+void drm_debugfs_connector_remove(struct drm_connector *connector)
+{
+	if (!connector->debugfs_entry)
+		return;
+
+	debugfs_remove_recursive(connector->debugfs_entry);
+
+	connector->debugfs_entry = NULL;
+}
+
 #endif /* CONFIG_DEBUG_FS */
 
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 8af71a8..57ecc42 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1419,6 +1419,8 @@ extern int drm_debugfs_create_files(const struct drm_info_list *files,
 extern int drm_debugfs_remove_files(const struct drm_info_list *files,
 				    int count, struct drm_minor *minor);
 extern int drm_debugfs_cleanup(struct drm_minor *minor);
+extern int drm_debugfs_connector_add(struct drm_connector *connector);
+extern void drm_debugfs_connector_remove(struct drm_connector *connector);
 #else
 static inline int drm_debugfs_init(struct drm_minor *minor, int minor_id,
 				   struct dentry *root)
@@ -1443,6 +1445,15 @@ static inline int drm_debugfs_cleanup(struct drm_minor *minor)
 {
 	return 0;
 }
+
+static inline int drm_debugfs_connector_add(struct drm_connector *connector)
+{
+	return 0;
+}
+static inline void drm_debugfs_connector_remove(struct drm_connector *connector)
+{
+}
+
 #endif
 
 				/* Info file support */
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 40f6588..67a33bc 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -549,6 +549,8 @@ struct drm_connector {
 	int audio_latency[2];
 	int null_edid_counter; /* needed to workaround some HW bugs where we get all 0s */
 	unsigned bad_edid_counter;
+
+	struct dentry *debugfs_entry;
 };
 
 /**
-- 
1.9.3