drm/i915/dp_mst: Move clearing the ACT sent flag closer to its polling

During transcoder enabling we'll configure the transcoder in MST mode
and enable the VC payload allocation, which will start the ACT sequence.
Before waiting for the ACT sequence completion, we need to clear the ACT
sent flag, but based on the above we can do this right before enabling
the transcoder.

For clarity, move the flag clearing closer to where we wait for it.

While at it also factor out some common code.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200616141855.746-3-imre.deak@intel.com

drivers/gpu/drm/i915/display/intel_dp_mst.c

@@ -318,6 +318,25 @@ intel_dp_mst_atomic_check(struct drm_connector *connector,
 	return ret;
 }
 
+static void clear_act_sent(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+
+	intel_de_write(i915, intel_dp->regs.dp_tp_status,
+		       intel_de_read(i915, intel_dp->regs.dp_tp_status));
+}
+
+static void wait_for_act_sent(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+
+	if (intel_de_wait_for_set(i915, intel_dp->regs.dp_tp_status,
+				  DP_TP_STATUS_ACT_SENT, 1))
+		drm_err(&i915->drm, "Timed out waiting for ACT sent\n");
+
+	drm_dp_check_act_status(&intel_dp->mst_mgr);
+}
+
 static void intel_mst_disable_dp(struct intel_atomic_state *state,
 				 struct intel_encoder *encoder,
 				 const struct intel_crtc_state *old_crtc_state,
@@ -378,11 +397,7 @@ static void intel_mst_post_disable_dp(struct intel_atomic_state *state,
 		       TRANS_DDI_FUNC_CTL(old_crtc_state->cpu_transcoder),
 		       val);
 
-	if (intel_de_wait_for_set(dev_priv, intel_dp->regs.dp_tp_status,
-				  DP_TP_STATUS_ACT_SENT, 1))
-		drm_err(&dev_priv->drm,
-			"Timed out waiting for ACT sent when disabling\n");
-	drm_dp_check_act_status(&intel_dp->mst_mgr);
+	wait_for_act_sent(intel_dp);
 
 	drm_dp_mst_deallocate_vcpi(&intel_dp->mst_mgr, connector->port);
 
@@ -453,7 +468,6 @@ static void intel_mst_pre_enable_dp(struct intel_atomic_state *state,
 	struct intel_connector *connector =
 		to_intel_connector(conn_state->connector);
 	int ret;
-	u32 temp;
 	bool first_mst_stream;
 
 	/* MST encoders are bound to a crtc, not to a connector,
@@ -486,8 +500,6 @@ static void intel_mst_pre_enable_dp(struct intel_atomic_state *state,
 		drm_err(&dev_priv->drm, "failed to allocate vcpi\n");
 
 	intel_dp->active_mst_links++;
-	temp = intel_de_read(dev_priv, intel_dp->regs.dp_tp_status);
-	intel_de_write(dev_priv, intel_dp->regs.dp_tp_status, temp);
 
 	ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr);
 
@@ -518,16 +530,14 @@ static void intel_mst_enable_dp(struct intel_atomic_state *state,
 
 	drm_WARN_ON(&dev_priv->drm, pipe_config->has_pch_encoder);
 
+	clear_act_sent(intel_dp);
+
 	intel_ddi_enable_transcoder_func(encoder, pipe_config);
 
 	drm_dbg_kms(&dev_priv->drm, "active links %d\n",
 		    intel_dp->active_mst_links);
 
-	if (intel_de_wait_for_set(dev_priv, intel_dp->regs.dp_tp_status,
-				  DP_TP_STATUS_ACT_SENT, 1))
-		drm_err(&dev_priv->drm, "Timed out waiting for ACT sent\n");
-
-	drm_dp_check_act_status(&intel_dp->mst_mgr);
+	wait_for_act_sent(intel_dp);
 
 	drm_dp_update_payload_part2(&intel_dp->mst_mgr);