drm: Add ratelimited versions of the DRM_DEBUG* macros

There's a couple of places where this would be useful for drivers (such
as reporting DP aux transaction timeouts).
Signed-off-by: Lyude <cpaul@redhat.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1470443443-27252-7-git-send-email-cpaul@redhat.com

include/drm/drmP.h

@@ -232,6 +232,36 @@ void drm_err(const char *format, ...);
 			drm_ut_debug_printk(__func__, fmt, ##args);	\
 	} while (0)
 
+#define _DRM_DEFINE_DEBUG_RATELIMITED(level, fmt, args...)		\
+	do {								\
+		if (unlikely(drm_debug & DRM_UT_ ## level)) {		\
+			static DEFINE_RATELIMIT_STATE(			\
+				_rs,					\
+				DEFAULT_RATELIMIT_INTERVAL,		\
+				DEFAULT_RATELIMIT_BURST);		\
+									\
+			if (__ratelimit(&_rs)) {			\
+				drm_ut_debug_printk(__func__, fmt,	\
+						    ##args);		\
+			}						\
+		}							\
+	} while (0)
+
+/**
+ * Rate limited debug output. Like DRM_DEBUG() but won't flood the log.
+ *
+ * \param fmt printf() like format string.
+ * \param arg arguments
+ */
+#define DRM_DEBUG_RATELIMITED(fmt, args...)				\
+	_DRM_DEFINE_DEBUG_RATELIMITED(CORE, fmt, ##args)
+#define DRM_DEBUG_DRIVER_RATELIMITED(fmt, args...)			\
+	_DRM_DEFINE_DEBUG_RATELIMITED(DRIVER, fmt, ##args)
+#define DRM_DEBUG_KMS_RATELIMITED(fmt, args...)				\
+	_DRM_DEFINE_DEBUG_RATELIMITED(KMS, fmt, ##args)
+#define DRM_DEBUG_PRIME_RATELIMITED(fmt, args...)			\
+	_DRM_DEFINE_DEBUG_RATELIMITED(PRIME, fmt, ##args)
+
 /*@}*/
 
 /***********************************************************************/