[PATCH 1/3] drm/i915/tgl+: Fix DP MST ACT status handling

[Imre Deak]

On TGL+ the master transcoder's DP_TP_STATUS register should be used for
the MST ACT status handling, so make sure we do that even in case of
mulitple streams.

This fixes an ACT timeout problem during disabling when using multiple
streams. Not sure why this was not a problem during enabling (even the
slave's DP_TP_STATUS signaled ACT correctly), but following the spec
works in that case too, so let's do that.

There is one more place using DP_TP_STATUS, FEC enabling, but I haven't
found in BSpec which register to use in that case, so I leave the
clarification of that for later.

BSpec: 49190

Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp_mst.c | 47 +++++++++++++++++----
 1 file changed, 39 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 2e6c6375a23b..e7430a57d771 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -317,6 +317,40 @@ intel_dp_mst_atomic_check(struct drm_connector *connector,
 	return ret;
 }
 
+static i915_reg_t
+master_dp_tp_status_reg(const struct intel_crtc_state *crtc_state,
+			const struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *dev_priv = to_i915(crtc_state->uapi.crtc->dev);
+
+	if (INTEL_GEN(dev_priv) >= 12)
+		return TGL_DP_TP_STATUS(crtc_state->mst_master_transcoder);
+
+	return intel_dp->regs.dp_tp_status;
+}
+
+static void clear_act_sent(const struct intel_crtc_state *crtc_state,
+			   const struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
+	i915_reg_t dp_tp_status_reg =
+		master_dp_tp_status_reg(crtc_state, intel_dp);
+
+	intel_de_write(i915, dp_tp_status_reg,
+		       intel_de_read(i915, dp_tp_status_reg));
+}
+
+static bool wait_for_act_sent(const struct intel_crtc_state *crtc_state,
+			      const struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
+	i915_reg_t dp_tp_status_reg =
+		master_dp_tp_status_reg(crtc_state, intel_dp);
+
+	return intel_de_wait_for_set(i915, dp_tp_status_reg,
+				     DP_TP_STATUS_ACT_SENT, 1) == 0;
+}
+
 static void intel_mst_disable_dp(struct intel_atomic_state *state,
 				 struct intel_encoder *encoder,
 				 const struct intel_crtc_state *old_crtc_state,
@@ -377,8 +411,7 @@ 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))
+	if (!wait_for_act_sent(old_crtc_state, intel_dp))
 		drm_err(&dev_priv->drm,
 			"Timed out waiting for ACT sent when disabling\n");
 	drm_dp_check_act_status(&intel_dp->mst_mgr);
@@ -452,7 +485,6 @@ 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,
@@ -485,8 +517,8 @@ 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);
+
+	clear_act_sent(pipe_config, intel_dp);
 
 	ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr);
 
@@ -522,9 +554,8 @@ static void intel_mst_enable_dp(struct intel_atomic_state *state,
 	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");
+	if (!wait_for_act_sent(pipe_config, intel_dp))
+		drm_err(&dev_priv->drm, "Timed out waiting for ACT sent when enabling\n");
 
 	drm_dp_check_act_status(&intel_dp->mst_mgr);
 
-- 
2.23.1