drm/debugfs: add a "force" file per connector

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@intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

4 files changed, 143 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index c50c827cefb6..c304e5650bc8 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -881,6 +881,8 @@ 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);
@@ -931,7 +933,19 @@ 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);
 
@@ -944,6 +958,7 @@ 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 b4b51d46f339..8ab3f3e38643 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 8af71a8e2c00..57ecc421b19c 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 5512c9968d77..d4b0a6a4ad9b 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -545,6 +545,8 @@ 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;
 };
 
 /**