diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index f9888c3..38ffcb4 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -26,7 +26,19 @@
 #include <linux/types.h>
 #include <linux/i2c.h>
 
-/* From the VESA DisplayPort spec */
+/*
+ * Unless otherwise noted, all values are from the DP 1.1a spec.  Note that
+ * DP and DPCD versions are independent.  Differences from 1.0 are not noted,
+ * 1.0 devices basically don't exist in the wild.
+ *
+ * Abbreviations, in chronological order:
+ *
+ * eDP: Embedded DisplayPort version 1
+ * DPI: DisplayPort Interoperability Guideline v1.1a
+ * 1.2: DisplayPort 1.2
+ *
+ * 1.2 formally includes both eDP and DPI definitions.
+ */
 
 #define AUX_NATIVE_WRITE	0x8
 #define AUX_NATIVE_READ		0x9
@@ -53,7 +65,7 @@
 
 #define DP_MAX_LANE_COUNT                   0x002
 # define DP_MAX_LANE_COUNT_MASK		    0x1f
-# define DP_TPS3_SUPPORTED		    (1 << 6)
+# define DP_TPS3_SUPPORTED		    (1 << 6) /* 1.2 */
 # define DP_ENHANCED_FRAME_CAP		    (1 << 7)
 
 #define DP_MAX_DOWNSPREAD                   0x003
@@ -69,16 +81,16 @@
 /* 10b = TMDS or HDMI */
 /* 11b = Other */
 # define DP_FORMAT_CONVERSION               (1 << 3)
-# define DP_DETAILED_CAP_INFO_AVAILABLE	    (1 << 4)
+# define DP_DETAILED_CAP_INFO_AVAILABLE	    (1 << 4) /* DPI */
 
 #define DP_MAIN_LINK_CHANNEL_CODING         0x006
 
 #define DP_DOWN_STREAM_PORT_COUNT	    0x007
 # define DP_PORT_COUNT_MASK		    0x0f
-# define DP_MSA_TIMING_PAR_IGNORED	    (1 << 6)
+# define DP_MSA_TIMING_PAR_IGNORED	    (1 << 6) /* eDP */
 # define DP_OUI_SUPPORT			    (1 << 7)
 
-#define DP_I2C_SPEED_CAP		    0x00c
+#define DP_I2C_SPEED_CAP		    0x00c    /* DPI */
 # define DP_I2C_SPEED_1K		    0x01
 # define DP_I2C_SPEED_5K		    0x02
 # define DP_I2C_SPEED_10K		    0x04
@@ -86,16 +98,16 @@
 # define DP_I2C_SPEED_400K		    0x10
 # define DP_I2C_SPEED_1M		    0x20
 
-#define DP_EDP_CONFIGURATION_CAP            0x00d
-#define DP_TRAINING_AUX_RD_INTERVAL         0x00e
+#define DP_EDP_CONFIGURATION_CAP            0x00d   /* XXX 1.2? */
+#define DP_TRAINING_AUX_RD_INTERVAL         0x00e   /* XXX 1.2? */
 
 /* Multiple stream transport */
-#define DP_MSTM_CAP			    0x021
+#define DP_MSTM_CAP			    0x021   /* 1.2 */
 # define DP_MST_CAP			    (1 << 0)
 
-#define DP_PSR_SUPPORT                      0x070
+#define DP_PSR_SUPPORT                      0x070   /* XXX 1.2? */
 # define DP_PSR_IS_SUPPORTED                1
-#define DP_PSR_CAPS                         0x071
+#define DP_PSR_CAPS                         0x071   /* XXX 1.2? */
 # define DP_PSR_NO_TRAIN_ON_EXIT            1
 # define DP_PSR_SETUP_TIME_330              (0 << 1)
 # define DP_PSR_SETUP_TIME_275              (1 << 1)
@@ -136,7 +148,7 @@
 #define	DP_LINK_BW_SET		            0x100
 # define DP_LINK_BW_1_62		    0x06
 # define DP_LINK_BW_2_7			    0x0a
-# define DP_LINK_BW_5_4			    0x14
+# define DP_LINK_BW_5_4			    0x14    /* 1.2 */
 
 #define DP_LANE_COUNT_SET	            0x101
 # define DP_LANE_COUNT_MASK		    0x0f
@@ -146,7 +158,7 @@
 # define DP_TRAINING_PATTERN_DISABLE	    0
 # define DP_TRAINING_PATTERN_1		    1
 # define DP_TRAINING_PATTERN_2		    2
-# define DP_TRAINING_PATTERN_3		    3
+# define DP_TRAINING_PATTERN_3		    3	    /* 1.2 */
 # define DP_TRAINING_PATTERN_MASK	    0x3
 
 # define DP_LINK_QUAL_PATTERN_DISABLE	    (0 << 2)
@@ -187,22 +199,22 @@
 
 #define DP_DOWNSPREAD_CTRL		    0x107
 # define DP_SPREAD_AMP_0_5		    (1 << 4)
-# define DP_MSA_TIMING_PAR_IGNORE_EN	    (1 << 7)
+# define DP_MSA_TIMING_PAR_IGNORE_EN	    (1 << 7) /* eDP */
 
 #define DP_MAIN_LINK_CHANNEL_CODING_SET	    0x108
 # define DP_SET_ANSI_8B10B		    (1 << 0)
 
-#define DP_I2C_SPEED_CONTROL_STATUS	    0x109
+#define DP_I2C_SPEED_CONTROL_STATUS	    0x109   /* DPI */
 /* bitmask as for DP_I2C_SPEED_CAP */
 
-#define DP_EDP_CONFIGURATION_SET            0x10a
+#define DP_EDP_CONFIGURATION_SET            0x10a   /* XXX 1.2? */
 
-#define DP_MSTM_CTRL			    0x111
+#define DP_MSTM_CTRL			    0x111   /* 1.2 */
 # define DP_MST_EN			    (1 << 0)
 # define DP_UP_REQ_EN			    (1 << 1)
 # define DP_UPSTREAM_IS_SRC		    (1 << 2)
 
-#define DP_PSR_EN_CFG			    0x170
+#define DP_PSR_EN_CFG			    0x170   /* XXX 1.2? */
 # define DP_PSR_ENABLE			    (1 << 0)
 # define DP_PSR_MAIN_LINK_ACTIVE	    (1 << 1)
 # define DP_PSR_CRC_VERIFICATION	    (1 << 2)
@@ -277,14 +289,14 @@
 # define DP_SET_POWER_D0                    0x1
 # define DP_SET_POWER_D3                    0x2
 
-#define DP_PSR_ERROR_STATUS                 0x2006
+#define DP_PSR_ERROR_STATUS                 0x2006  /* XXX 1.2? */
 # define DP_PSR_LINK_CRC_ERROR              (1 << 0)
 # define DP_PSR_RFB_STORAGE_ERROR           (1 << 1)
 
-#define DP_PSR_ESI                          0x2007
+#define DP_PSR_ESI                          0x2007  /* XXX 1.2? */
 # define DP_PSR_CAPS_CHANGE                 (1 << 0)
 
-#define DP_PSR_STATUS                       0x2008
+#define DP_PSR_STATUS                       0x2008  /* XXX 1.2? */
 # define DP_PSR_SINK_INACTIVE               0
 # define DP_PSR_SINK_ACTIVE_SRC_SYNCED      1
 # define DP_PSR_SINK_ACTIVE_RFB             2