drm/i915/skl: Implement WaDisableHBR2

v2: Use the recently introduced INTEL_REVID() and SKL_REVID defines
    (Nick Hoath)

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89554
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -134,7 +134,10 @@ intel_dp_max_link_bw(struct intel_dp *intel_dp)
 	case DP_LINK_BW_2_7:
 		break;
 	case DP_LINK_BW_5_4: /* 1.2 capable displays may advertise higher bw */
-		if (((IS_HASWELL(dev) && !IS_HSW_ULX(dev)) ||
+		if (IS_SKYLAKE(dev) && INTEL_REVID(dev) <= SKL_REVID_B0)
+			/* WaDisableHBR2:skl */
+			max_link_bw = DP_LINK_BW_2_7;
+		else if (((IS_HASWELL(dev) && !IS_HSW_ULX(dev)) ||
 		     INTEL_INFO(dev)->gen >= 8) &&
 		    intel_dp->dpcd[DP_DPCD_REV] >= 0x12)
 			max_link_bw = DP_LINK_BW_5_4;