drm/i915/dp: only use training pattern 3 on platforms that support it

Ivybridge + 30" monitor prints a drm error on every modeset, since IVB
doesn't support DP3 we should even bother trying to use it.

This regression has been introduced in

commit 06ea66b6bb445043dc25a9626254d5c130093199
Author: Todd Previte <tprevite@gmail.com>
Date:   Mon Jan 20 10:19:39 2014 -0700

    drm/i915: Enable 5.4Ghz (HBR2) link rate for Displayport 1.2-capable
devices

Reported-by: Dave Airlie <airlied@redhat.com>
Reference: http://mid.gmane.org/1414566170-9868-1-git-send-email-airlied@gmail.com
Cc: Todd Previte <tprevite@gmail.com>
Cc: stable@vger.kernel.org (3.15+)
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 464d8ad..5ad45bf 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3731,9 +3731,10 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
                }
        }
 
-       /* Training Pattern 3 support */
+       /* Training Pattern 3 support, both source and sink */
        if (intel_dp->dpcd[DP_DPCD_REV] >= 0x12 &&
-           intel_dp->dpcd[DP_MAX_LANE_COUNT] & DP_TPS3_SUPPORTED) {
+           intel_dp->dpcd[DP_MAX_LANE_COUNT] & DP_TPS3_SUPPORTED &&
+           (IS_HASWELL(dev_priv) || INTEL_INFO(dev_priv)->gen >= 8)) {
                intel_dp->use_tps3 = true;
                DRM_DEBUG_KMS("Displayport TPS3 supported\n");
        } else