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/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
index 800055c..206a4fe 100644
--- a/drivers/gpu/drm/drm_debugfs.c
+++ b/drivers/gpu/drm/drm_debugfs.c
@@ -36,6 +36,7 @@
 #include <linux/export.h>
 #include <drm/drmP.h>
 #include <drm/drm_edid.h>
+#include <drm/drm_atomic.h>
 #include "drm_internal.h"
 
 #if defined(CONFIG_DEBUG_FS)
@@ -163,6 +164,14 @@ int drm_debugfs_init(struct drm_minor *minor, int minor_id,
 		return ret;
 	}
 
+	if (drm_core_check_feature(dev, DRIVER_ATOMIC)) {
+		ret = drm_atomic_debugfs_init(minor);
+		if (ret) {
+			DRM_ERROR("Failed to create atomic debugfs files\n");
+			return ret;
+		}
+	}
+
 	if (dev->driver->debugfs_init) {
 		ret = dev->driver->debugfs_init(minor);
 		if (ret) {