[Intel-gfx] [PATCH 18/29] drm/i915/dp: Wait for FEC detected status in the sink

[Imre Deak]

As required by the DP standard wait for the sink to detect the FEC
decode enabling symbol sent by the source.

Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/display/intel_ddi.c    | 73 +++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_ddi.h    |  3 +
 drivers/gpu/drm/i915/display/intel_dp_mst.c |  4 ++
 3 files changed, 80 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index dac3b59758af7..6f9d0f2ff3d9a 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -25,6 +25,7 @@
  *
  */
 
+#include <linux/iopoll.h>
 #include <linux/string_helpers.h>
 
 #include <drm/display/drm_scdc_helper.h>
@@ -2220,6 +2221,74 @@ static void intel_dp_sink_set_fec_ready(struct intel_dp *intel_dp,
 	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_FEC_CONFIGURATION, DP_FEC_READY) <= 0)
 		drm_dbg_kms(&i915->drm,
 			    "Failed to set FEC_READY in the sink\n");
+
+	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_FEC_STATUS,
+			       DP_FEC_DECODE_EN_DETECTED | DP_FEC_DECODE_DIS_DETECTED) <= 0)
+		drm_dbg_kms(&i915->drm, "Failed to clear FEC detected flags\n");
+}
+
+static int read_fec_detected_status(struct drm_dp_aux *aux)
+{
+	int ret;
+	u8 status;
+
+	ret = drm_dp_dpcd_readb(aux, DP_FEC_STATUS, &status);
+	if (ret < 0)
+		return ret;
+
+	return status;
+}
+
+static void wait_for_fec_detected(struct drm_dp_aux *aux, bool enabled)
+{
+	struct drm_i915_private *i915 = to_i915(aux->drm_dev);
+	int mask = enabled ? DP_FEC_DECODE_EN_DETECTED : DP_FEC_DECODE_DIS_DETECTED;
+	int status;
+	int err;
+
+	err = readx_poll_timeout(read_fec_detected_status, aux, status,
+				 status & mask || status < 0,
+				 10000, 200000);
+
+	if (!err && status >= 0)
+		return;
+
+	if (err == -ETIMEDOUT)
+		drm_err(&i915->drm, "Timeout waiting for FEC %s to get detected\n",
+			str_enabled_disabled(enabled));
+	else
+		drm_dbg_kms(&i915->drm, "FEC detected status read error: %d\n", status);
+}
+
+void intel_ddi_wait_for_fec_status(struct intel_encoder *encoder,
+				   const struct intel_crtc_state *crtc_state,
+				   bool enabled)
+{
+	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
+	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+	int ret;
+
+	if (!crtc_state->fec_enable)
+		return;
+
+	if (enabled)
+		ret = intel_de_wait_for_set(i915, dp_tp_status_reg(encoder, crtc_state),
+					    DP_TP_STATUS_FEC_ENABLE_LIVE, 1);
+	else
+		ret = intel_de_wait_for_clear(i915, dp_tp_status_reg(encoder, crtc_state),
+					      DP_TP_STATUS_FEC_ENABLE_LIVE, 1);
+
+	if (ret)
+		drm_err(&i915->drm,
+			"Timeout waiting for FEC live state to get %s\n",
+			str_enabled_disabled(enabled));
+
+	/*
+	 * At least the Synoptics MST hub doesn't set the detected flag for
+	 * FEC decoding disabling so skip waiting for that.
+	 */
+	if (enabled)
+		wait_for_fec_detected(&intel_dp->aux, enabled);
 }
 
 static void intel_ddi_enable_fec(struct intel_encoder *encoder,
@@ -2887,6 +2956,8 @@ static void intel_disable_ddi_buf(struct intel_encoder *encoder,
 	} else {
 		disable_ddi_buf(encoder, crtc_state);
 	}
+
+	intel_ddi_wait_for_fec_status(encoder, crtc_state, false);
 }
 
 static void intel_ddi_post_disable_dp(struct intel_atomic_state *state,
@@ -3248,6 +3319,8 @@ static void intel_enable_ddi(struct intel_atomic_state *state,
 	if (!intel_crtc_is_bigjoiner_slave(crtc_state))
 		intel_ddi_enable_transcoder_func(encoder, crtc_state);
 
+	intel_ddi_wait_for_fec_status(encoder, crtc_state, true);
+
 	/* Enable/Disable DP2.0 SDP split config before transcoder */
 	intel_audio_sdp_split_update(crtc_state);
 
diff --git a/drivers/gpu/drm/i915/display/intel_ddi.h b/drivers/gpu/drm/i915/display/intel_ddi.h
index 4999c0ee229bd..e939b93fc81c2 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.h
+++ b/drivers/gpu/drm/i915/display/intel_ddi.h
@@ -60,6 +60,9 @@ void intel_ddi_disable_transcoder_func(const struct intel_crtc_state *crtc_state
 void intel_ddi_enable_transcoder_clock(struct intel_encoder *encoder,
 				       const struct intel_crtc_state *crtc_state);
 void intel_ddi_disable_transcoder_clock(const  struct intel_crtc_state *crtc_state);
+void intel_ddi_wait_for_fec_status(struct intel_encoder *encoder,
+				   const struct intel_crtc_state *crtc_state,
+				   bool enabled);
 void intel_ddi_set_dp_msa(const struct intel_crtc_state *crtc_state,
 			  const struct drm_connector_state *conn_state);
 bool intel_ddi_connector_get_hw_state(struct intel_connector *intel_connector);
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index b7a9ce40cf59a..a1ea75cd5ea84 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -853,6 +853,7 @@ static void intel_mst_enable_dp(struct intel_atomic_state *state,
 	struct drm_dp_mst_topology_state *mst_state =
 		drm_atomic_get_new_mst_topology_state(&state->base, &intel_dp->mst_mgr);
 	enum transcoder trans = pipe_config->cpu_transcoder;
+	bool first_mst_stream = intel_dp->active_mst_links == 1;
 
 	drm_WARN_ON(&dev_priv->drm, pipe_config->has_pch_encoder);
 
@@ -879,6 +880,9 @@ static void intel_mst_enable_dp(struct intel_atomic_state *state,
 
 	wait_for_act_sent(encoder, pipe_config);
 
+	if (first_mst_stream)
+		intel_ddi_wait_for_fec_status(encoder, pipe_config, true);
+
 	drm_dp_add_payload_part2(&intel_dp->mst_mgr, &state->base,
 				 drm_atomic_get_mst_payload_state(mst_state, connector->port));
 
-- 
2.39.2