drm/radeon/kms: implement display watermark support for evergreen

Improper display watermarks can result in underflow to the display
controllers which can cause flickering or other artifacts.
This patch implements display watermark support and line buffer
allocation for evergreen asics.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/evergreend.h

@@ -412,6 +412,19 @@
 #define		SOFT_RESET_REGBB		       	(1 << 22)
 #define		SOFT_RESET_ORB				(1 << 23)
 
+/* display watermarks */
+#define	DC_LB_MEMORY_SPLIT				  0x6b0c
+#define	PRIORITY_A_CNT			                  0x6b18
+#define		PRIORITY_MARK_MASK			  0x7fff
+#define		PRIORITY_OFF				  (1 << 16)
+#define		PRIORITY_ALWAYS_ON			  (1 << 20)
+#define	PRIORITY_B_CNT			                  0x6b1c
+#define	PIPE0_ARBITRATION_CONTROL3			  0x0bf0
+#       define LATENCY_WATERMARK_MASK(x)                  ((x) << 16)
+#define	PIPE0_LATENCY_CONTROL			          0x0bf4
+#       define LATENCY_LOW_WATERMARK(x)                   ((x) << 0)
+#       define LATENCY_HIGH_WATERMARK(x)                  ((x) << 16)
+
 #define IH_RB_CNTL                                        0x3e00
 #       define IH_RB_ENABLE                               (1 << 0)
 #       define IH_IB_SIZE(x)                              ((x) << 1) /* log2 */