drm: Consolidate and document sysfs support

- remove docs for internal func, doesn't add value
- add short overview snippet instead explaining that drivers don't
  have to bother themselves with reg/unreg concerns
- drop the ttm comment about drmP.h, drmP.h is disappearing ...

Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170404095304.17599-2-daniel.vetter@ffwll.ch

Documentation/gpu/drm-uapi.rst

@@ -219,6 +219,16 @@ Debugfs Support
 .. kernel-doc:: drivers/gpu/drm/drm_debugfs.c
    :export:
 
+Sysfs Support
+=============
+
+.. kernel-doc:: drivers/gpu/drm/drm_sysfs.c
+   :doc: overview
+
+.. kernel-doc:: drivers/gpu/drm/drm_sysfs.c
+   :export:
+
+
 VBlank event handling
 =====================
 

drivers/gpu/drm/drm_sysfs.c

@@ -25,6 +25,20 @@
 #define to_drm_minor(d) dev_get_drvdata(d)
 #define to_drm_connector(d) dev_get_drvdata(d)
 
+/**
+ * DOC: overview
+ *
+ * DRM provides very little additional support to drivers for sysfs
+ * interactions, beyond just all the standard stuff. Drivers who want to expose
+ * additional sysfs properties and property groups can attach them at either
+ * &drm_device.dev or &drm_connector.kdev.
+ *
+ * Registration is automatically handled when calling drm_dev_register(), or
+ * drm_connector_register() in case of hot-plugged connectors. Unregistration is
+ * also automatically handled by drm_dev_unregister() and
+ * drm_connector_unregister().
+ */
+
 static struct device_type drm_sysfs_device_minor = {
 	.name = "drm_minor"
 };
@@ -250,15 +264,6 @@ static const struct attribute_group *connector_dev_groups[] = {
 	NULL
 };
 
-/**
- * drm_sysfs_connector_add - add a connector to sysfs
- * @connector: connector to add
- *
- * Create a connector device in sysfs, along with its associated connector
- * properties (so far, connection status, dpms, mode list and edid) and
- * generate a hotplug event so userspace knows there's a new connector
- * available.
- */
 int drm_sysfs_connector_add(struct drm_connector *connector)
 {
 	struct drm_device *dev = connector->dev;
@@ -285,19 +290,6 @@ int drm_sysfs_connector_add(struct drm_connector *connector)
 	return 0;
 }
 
-/**
- * drm_sysfs_connector_remove - remove an connector device from sysfs
- * @connector: connector to remove
- *
- * Remove @connector and its associated attributes from sysfs.  Note that
- * the device model core will take care of sending the "remove" uevent
- * at this time, so we don't need to do it.
- *
- * Note:
- * This routine should only be called if the connector was previously
- * successfully registered.  If @connector hasn't been registered yet,
- * you'll likely see a panic somewhere deep in sysfs code when called.
- */
 void drm_sysfs_connector_remove(struct drm_connector *connector)
 {
 	if (!connector->kdev)
@@ -333,20 +325,6 @@ static void drm_sysfs_release(struct device *dev)
 	kfree(dev);
 }
 
-/**
- * drm_sysfs_minor_alloc() - Allocate sysfs device for given minor
- * @minor: minor to allocate sysfs device for
- *
- * This allocates a new sysfs device for @minor and returns it. The device is
- * not registered nor linked. The caller has to use device_add() and
- * device_del() to register and unregister it.
- *
- * Note that dev_get_drvdata() on the new device will return the minor.
- * However, the device does not hold a ref-count to the minor nor to the
- * underlying drm_device. This is unproblematic as long as you access the
- * private data only in sysfs callbacks. device_del() disables those
- * synchronously, so they cannot be called after you cleanup a minor.
- */
 struct device *drm_sysfs_minor_alloc(struct drm_minor *minor)
 {
 	const char *minor_str;
@@ -384,15 +362,13 @@ err_free:
 }
 
 /**
- * drm_class_device_register - Register a struct device in the drm class.
+ * drm_class_device_register - register new device with the DRM sysfs class
+ * @dev: device to register
  *
- * @dev: pointer to struct device to register.
+ * Registers a new &struct device within the DRM sysfs class. Essentially only
- *
+ * used by ttm to have a place for its global settings. Drivers should never use
- * @dev should have all relevant members pre-filled with the exception
+ * this.
- * of the class member. In particular, the device_type member must
- * be set.
  */
-
 int drm_class_device_register(struct device *dev)
 {
 	if (!drm_class || IS_ERR(drm_class))
@@ -403,6 +379,14 @@ int drm_class_device_register(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(drm_class_device_register);
 
+/**
+ * drm_class_device_unregister - unregister device with the DRM sysfs class
+ * @dev: device to unregister
+ *
+ * Unregisters a &struct device from the DRM sysfs class. Essentially only used
+ * by ttm to have a place for its global settings. Drivers should never use
+ * this.
+ */
 void drm_class_device_unregister(struct device *dev)
 {
 	return device_unregister(dev);

include/drm/drmP.h

@@ -80,6 +80,7 @@
 #include <drm/drm_file.h>
 #include <drm/drm_debugfs.h>
 #include <drm/drm_ioctl.h>
+#include <drm/drm_sysfs.h>
 
 struct module;
 
@@ -512,10 +513,6 @@ static inline int drm_device_is_unplugged(struct drm_device *dev)
  * DMA quiscent + idle. DMA quiescent usually requires the hardware lock.
  */
 
-			       /* sysfs support (drm_sysfs.c) */
-extern void drm_sysfs_hotplug_event(struct drm_device *dev);
-
-
 /*@}*/
 
 /* returns true if currently okay to sleep */

include/drm/drm_sysfs.h

@@ -1,12 +1,12 @@
 #ifndef _DRM_SYSFS_H_
 #define _DRM_SYSFS_H_
 
-/**
+struct drm_device;
- * This minimalistic include file is intended for users (read TTM) that
+struct device;
- * don't want to include the full drmP.h file.
- */
 
 int drm_class_device_register(struct device *dev);
 void drm_class_device_unregister(struct device *dev);
 
+void drm_sysfs_hotplug_event(struct drm_device *dev);
+
 #endif