1 files changed, 22 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index f6a3fdd5589e..5ad45bfff3fe 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -2806,6 +2806,13 @@ intel_dp_dpcd_read_wake(struct drm_dp_aux *aux, unsigned int offset,
        ssize_t ret;
        int i;
+        /*
+         * Sometime we just get the same incorrect byte repeated
+         * over the entire buffer. Doing just one throw away read
+         * initially seems to "solve" it.
+         */
+        drm_dp_dpcd_read(aux, DP_DPCD_REV, buffer, 1);
        for (i = 0; i < 3; i++) {
                ret = drm_dp_dpcd_read(aux, offset, buffer, size);
                if (ret == size)
@@ -3724,9 +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
@@ -4491,6 +4499,18 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
        if (intel_dig_port->base.type != INTEL_OUTPUT_EDP)
                intel_dig_port->base.type = INTEL_OUTPUT_DISPLAYPORT;
+        if (long_hpd && intel_dig_port->base.type == INTEL_OUTPUT_EDP) {
+                /*
+                 * vdd off can generate a long pulse on eDP which
+                 * would require vdd on to handle it, and thus we
+                 * would end up in an endless cycle of
+                 * "vdd off -> long hpd -> vdd on -> detect -> vdd off -> ..."
+                 */
+                DRM_DEBUG_KMS("ignoring long hpd on eDP port %c\n",
+                              port_name(intel_dig_port->port));
+                return false;
+        }
        DRM_DEBUG_KMS("got hpd irq on port %c - %s\n",
                      port_name(intel_dig_port->port),
                      long_hpd ? "long" : "short");