drm/atomic: add debugfs file to dump out atomic state

Useful to dump current state from debugfs, if turning on the drm.debug
bit is too much overhead.

The drm_state_dump() can also be used by drivers, for example to
implement a module param that dumps state on error irqs.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1478358492-30738-6-git-send-email-robdclark@gmail.com
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index 2d1e9c9..331bb10 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -366,6 +366,13 @@ int __must_check drm_atomic_check_only(struct drm_atomic_state *state);
 int __must_check drm_atomic_commit(struct drm_atomic_state *state);
 int __must_check drm_atomic_nonblocking_commit(struct drm_atomic_state *state);
 
+void drm_state_dump(struct drm_device *dev, struct drm_printer *p);
+
+#ifdef CONFIG_DEBUG_FS
+struct drm_minor;
+int drm_atomic_debugfs_init(struct drm_minor *minor);
+#endif
+
 #define for_each_connector_in_state(__state, connector, connector_state, __i) \
 	for ((__i) = 0;							\
 	     (__i) < (__state)->num_connector &&				\