drm/dp: Add HBR3 support in existing DRM DP helpers

Existing helpers add support upto HBR2. This patch
adds support for HBR3 rate (8.1 Gbps) introduced as
part of DP 1.4 specification.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1516660991-20697-1-git-send-email-manasi.d.navare@intel.com

drivers/gpu/drm/drm_dp_helper.c

@@ -146,6 +146,8 @@ u8 drm_dp_link_rate_to_bw_code(int link_rate)
 		return DP_LINK_BW_2_7;
 	case 540000:
 		return DP_LINK_BW_5_4;
+	case 810000:
+		return DP_LINK_BW_8_1;
 	}
 }
 EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code);
@@ -161,6 +163,8 @@ int drm_dp_bw_code_to_link_rate(u8 link_bw)
 		return 270000;
 	case DP_LINK_BW_5_4:
 		return 540000;
+	case DP_LINK_BW_8_1:
+		return 810000;
 	}
 }
 EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -2087,6 +2087,9 @@ static bool drm_dp_get_vc_payload_bw(int dp_link_bw,
 	case DP_LINK_BW_5_4:
 		*out = 10 * dp_link_count;
 		break;
+	case DP_LINK_BW_8_1:
+		*out = 15 * dp_link_count;
+		break;
 	}
 	return true;
 }

include/drm/drm_dp_helper.h

@@ -334,6 +334,7 @@
 # define DP_LINK_BW_1_62		    0x06
 # define DP_LINK_BW_2_7			    0x0a
 # define DP_LINK_BW_5_4			    0x14    /* 1.2 */
+# define DP_LINK_BW_8_1			    0x1e    /* 1.4 */
 
 #define DP_LANE_COUNT_SET	            0x101
 # define DP_LANE_COUNT_MASK		    0x0f