[v2,19/40] drm/i915/tgl: Select master transcoder in DP MST

Submitted by Lucas De Marchi on Aug. 17, 2019, 9:38 a.m.

Details

Message ID 20190817093902.2171-20-lucas.demarchi@intel.com
State New
Headers show
Series "Tiger Lake batch 3" ( rev: 4 3 2 ) in Intel GFX

Not browsing as part of any series.

Commit Message

Lucas De Marchi Aug. 17, 2019, 9:38 a.m.
From: José Roberto de Souza <jose.souza@intel.com>

On TGL the blending of all the streams have moved from DDI to
transcoder, so now every transcoder working over the same MST port must
send its stream to a master transcoder and master will send to DDI
respecting the time slots.

So here it is picking the lowest pipe/transcoder as it will be
enabled first and disabled last.
BSpec: 50493
BSpec: 49190

v2: Missed set mst_master_trans to TRANSCODER_INVALID when computing HSW
    encoder config. HSW CRT hw state readout calls
    hsw_crt_get_config()->intel_ddi_get_config() that will set
    mst_master_trans to TRANSCODER_INVALID causing the mismatch when
    verifying CRTC state after a modeset. (José)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
---
 drivers/gpu/drm/i915/display/intel_crt.c      |   2 +
 drivers/gpu/drm/i915/display/intel_ddi.c      |  17 ++
 drivers/gpu/drm/i915/display/intel_display.c  |  15 ++
 drivers/gpu/drm/i915/display/intel_display.h  |   3 +
 .../drm/i915/display/intel_display_types.h    |   3 +
 drivers/gpu/drm/i915/display/intel_dp_mst.c   | 159 +++++++++++++++++-
 drivers/gpu/drm/i915/display/intel_dp_mst.h   |   2 +
 drivers/gpu/drm/i915/i915_reg.h               |   3 +
 8 files changed, 201 insertions(+), 3 deletions(-)

Patch hide | download patch | download mbox

diff --git a/drivers/gpu/drm/i915/display/intel_crt.c b/drivers/gpu/drm/i915/display/intel_crt.c
index e6e8d4a82044..503135200cb3 100644
--- a/drivers/gpu/drm/i915/display/intel_crt.c
+++ b/drivers/gpu/drm/i915/display/intel_crt.c
@@ -416,6 +416,8 @@  static int hsw_crt_compute_config(struct intel_encoder *encoder,
 	/* FDI must always be 2.7 GHz */
 	pipe_config->port_clock = 135000 * 2;
 
+	pipe_config->mst_master_trans = TRANSCODER_INVALID;
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 1f591e69b742..50a26bea8cde 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -1840,6 +1840,12 @@  void intel_ddi_enable_transcoder_func(const struct intel_crtc_state *crtc_state)
 	} else if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST)) {
 		temp |= TRANS_DDI_MODE_SELECT_DP_MST;
 		temp |= DDI_PORT_WIDTH(crtc_state->lane_count);
+
+		if (INTEL_GEN(dev_priv) >= 12) {
+			enum transcoder master = crtc_state->mst_master_trans;
+
+			temp |= TRANS_DDI_MST_TRANSPORT_SELECT_DPTP(master);
+		}
 	} else {
 		temp |= TRANS_DDI_MODE_SELECT_DP_SST;
 		temp |= DDI_PORT_WIDTH(crtc_state->lane_count);
@@ -3861,6 +3867,8 @@  void intel_ddi_get_config(struct intel_encoder *encoder,
 		break;
 	}
 
+	pipe_config->mst_master_trans = TRANSCODER_INVALID;
+
 	switch (temp & TRANS_DDI_MODE_SELECT_MASK) {
 	case TRANS_DDI_MODE_SELECT_HDMI:
 		pipe_config->has_hdmi_sink = true;
@@ -3896,6 +3904,13 @@  void intel_ddi_get_config(struct intel_encoder *encoder,
 		pipe_config->output_types |= BIT(INTEL_OUTPUT_DP_MST);
 		pipe_config->lane_count =
 			((temp & DDI_PORT_WIDTH_MASK) >> DDI_PORT_WIDTH_SHIFT) + 1;
+
+		if (INTEL_GEN(dev_priv) >= 12) {
+			temp = temp & TRANS_DDI_MST_TRANSPORT_SELECT_MASK;
+			temp = temp >> TRANS_DDI_MST_TRANSPORT_SELECT_SHIFT;
+			pipe_config->mst_master_trans = temp;
+		}
+
 		intel_dp_get_m_n(intel_crtc, pipe_config);
 		break;
 	default:
@@ -3998,6 +4013,8 @@  static int intel_ddi_compute_config(struct intel_encoder *encoder,
 
 	intel_ddi_compute_min_voltage_level(dev_priv, pipe_config);
 
+	pipe_config->mst_master_trans = TRANSCODER_INVALID;
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index ddb8436e2208..109d4fd961c6 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -47,6 +47,7 @@ 
 #include "display/intel_crt.h"
 #include "display/intel_ddi.h"
 #include "display/intel_dp.h"
+#include "display/intel_dp_mst.h"
 #include "display/intel_dsi.h"
 #include "display/intel_dvo.h"
 #include "display/intel_gmbus.h"
@@ -12138,6 +12139,14 @@  static void intel_dump_pipe_config(const struct intel_crtc_state *pipe_config,
 
 	intel_dpll_dump_hw_state(dev_priv, &pipe_config->dpll_hw_state);
 
+	if (INTEL_GEN(dev_priv) >= 12 &&
+	    intel_crtc_has_type(pipe_config, INTEL_OUTPUT_DP_MST)) {
+		enum transcoder master = pipe_config->mst_master_trans;
+
+		DRM_DEBUG_KMS("master mst cpu_transcoder: %s\n",
+			      transcoder_name(master));
+	}
+
 dump_planes:
 	if (!state)
 		return;
@@ -12821,6 +12830,8 @@  intel_pipe_config_compare(const struct intel_crtc_state *current_config,
 	PIPE_CONF_CHECK_INFOFRAME(hdmi);
 	PIPE_CONF_CHECK_INFOFRAME(drm);
 
+	PIPE_CONF_CHECK_I(mst_master_trans);
+
 #undef PIPE_CONF_CHECK_X
 #undef PIPE_CONF_CHECK_I
 #undef PIPE_CONF_CHECK_BOOL
@@ -13597,6 +13608,10 @@  static int intel_atomic_check(struct drm_device *dev,
 	int ret, i;
 	bool any_ms = state->cdclk.force_min_cdclk_changed;
 
+	ret = intel_dp_mst_atomic_add_affected_crtcs(state);
+	if (ret)
+		return ret;
+
 	/* Catch I915_MODE_FLAG_INHERITED */
 	for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
 					    new_crtc_state, i) {
diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h
index b63fb7a4599e..282e8d8f1cc1 100644
--- a/drivers/gpu/drm/i915/display/intel_display.h
+++ b/drivers/gpu/drm/i915/display/intel_display.h
@@ -91,6 +91,8 @@  enum pipe {
 #define pipe_name(p) ((p) + 'A')
 
 enum transcoder {
+	TRANSCODER_INVALID = -1,
+
 	/*
 	 * The following transcoders have a 1:1 transcoder -> pipe mapping,
 	 * keep their values fixed: the code assumes that TRANSCODER_A=0, the
@@ -132,6 +134,7 @@  static inline const char *transcoder_name(enum transcoder transcoder)
 		return "DSI A";
 	case TRANSCODER_DSI_C:
 		return "DSI C";
+	case TRANSCODER_INVALID:
 	default:
 		return "<invalid>";
 	}
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 3c1a5f3e1d22..b7da955954b7 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -984,6 +984,9 @@  struct intel_crtc_state {
 
 	/* Forward Error correction State */
 	bool fec_enable;
+
+	/* Master transcoder for all streams, only used on TGL+ */
+	enum transcoder mst_master_trans;
 };
 
 struct intel_crtc {
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index f52cdd4ca877..670a12fd2f27 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -87,6 +87,50 @@  static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
 	return 0;
 }
 
+/*
+ * Iterate over all the CRTCs and return the transcoder of the lowest CRTC that
+ * share the same MST connector.
+ */
+static enum transcoder
+mst_compute_master_trans(struct drm_atomic_state *state,
+			 struct drm_connector *mst_conn)
+{
+	struct intel_connector *intel_mst_conn = to_intel_connector(mst_conn);
+	struct intel_atomic_state *intel_state = to_intel_atomic_state(state);
+	struct drm_i915_private *dev_priv = to_i915(state->dev);
+	struct intel_crtc_state *intel_crtc_state;
+	struct intel_crtc *intel_crtc;
+	int i;
+
+	if (INTEL_GEN(dev_priv) < 12)
+		return TRANSCODER_INVALID;
+
+	/* Iterate from the lowest to the highest pipe */
+	for_each_new_intel_crtc_in_state(intel_state, intel_crtc, intel_crtc_state, i) {
+		struct intel_digital_connector_state *intel_conn_state;
+		struct intel_connector *intel_conn;
+		int j;
+
+		if (!intel_crtc_state->base.active)
+			continue;
+
+		for_each_new_intel_connector_in_state(intel_state, intel_conn,
+						      intel_conn_state, j) {
+			/* Only care about connectors of this CRTC */
+			if (intel_conn_state->base.crtc !=
+			    intel_crtc_state->base.crtc)
+				continue;
+
+			if (intel_conn->mst_port != intel_mst_conn->mst_port)
+				continue;
+
+			return intel_crtc_state->cpu_transcoder;
+		}
+	}
+
+	return TRANSCODER_INVALID;
+}
+
 static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
 				       struct intel_crtc_state *pipe_config,
 				       struct drm_connector_state *conn_state)
@@ -94,14 +138,15 @@  static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
 	struct intel_dp *intel_dp = &intel_mst->primary->dp;
-	struct intel_connector *connector =
-		to_intel_connector(conn_state->connector);
+	struct drm_connector *connector = conn_state->connector;
+	struct intel_connector *intel_connector = to_intel_connector(connector);
 	struct intel_digital_connector_state *intel_conn_state =
 		to_intel_digital_connector_state(conn_state);
 	const struct drm_display_mode *adjusted_mode =
 		&pipe_config->base.adjusted_mode;
-	void *port = connector->port;
+	void *port = intel_connector->port;
 	struct link_config_limits limits;
+	enum transcoder master;
 	int ret;
 
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
@@ -146,6 +191,51 @@  static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
 
 	intel_ddi_compute_min_voltage_level(dev_priv, pipe_config);
 
+	master = mst_compute_master_trans(conn_state->state, connector);
+	pipe_config->mst_master_trans = master;
+
+	return 0;
+}
+
+static int
+intel_dp_mst_master_trans_check(struct drm_connector *conn,
+				struct drm_connector_state *new_conn_state)
+{
+	struct drm_i915_private *dev_priv = to_i915(conn->dev);
+	struct drm_atomic_state *state = new_conn_state->state;
+	struct drm_connector_state *old_conn_state =
+		drm_atomic_get_old_connector_state(state, conn);
+	struct drm_crtc *new_crtc = new_conn_state->crtc;
+	struct drm_crtc *old_crtc = old_conn_state->crtc;
+	enum transcoder old_master_trans = TRANSCODER_INVALID;
+	enum transcoder new_master_trans = TRANSCODER_INVALID;
+	struct drm_crtc_state *new_crtc_state, *old_crtc_state;
+
+	if (INTEL_GEN(dev_priv) < 12)
+		return 0;
+
+	if (old_crtc) {
+		struct intel_crtc_state *intel_crtc_state;
+
+		old_crtc_state = drm_atomic_get_new_crtc_state(state, old_crtc);
+		intel_crtc_state = to_intel_crtc_state(old_crtc_state);
+		old_master_trans = intel_crtc_state->mst_master_trans;
+	}
+
+	if (new_crtc) {
+		struct intel_crtc_state *intel_crtc_state;
+
+		new_crtc_state = drm_atomic_get_new_crtc_state(state, new_crtc);
+		intel_crtc_state = to_intel_crtc_state(new_crtc_state);
+		new_master_trans = mst_compute_master_trans(state, conn);
+	}
+
+	if (old_crtc && old_master_trans != new_master_trans)
+		old_crtc_state->mode_changed = true;
+
+	if (new_crtc && old_master_trans != new_master_trans)
+		new_crtc_state->mode_changed = true;
+
 	return 0;
 }
 
@@ -168,6 +258,10 @@  intel_dp_mst_atomic_check(struct drm_connector *connector,
 	if (ret)
 		return ret;
 
+	ret = intel_dp_mst_master_trans_check(connector, new_conn_state);
+	if (ret)
+		return ret;
+
 	if (!old_conn_state->crtc)
 		return 0;
 
@@ -666,3 +760,62 @@  intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port)
 	drm_dp_mst_topology_mgr_destroy(&intel_dp->mst_mgr);
 	/* encoders will get killed by normal cleanup */
 }
+
+/**
+ * intel_dp_mst_atomic_add_affected_crtcs - Add all CRTCs that share the MST
+ * stream with the CRTCs in the current atomic state.
+ * @state: state to add CRTCs
+ *
+ * It is needed add the CRTCs trigger a call to atomic_check() to
+ * every connector attached to the CRTC in case a new master transcoder will
+ * be needed.
+ */
+int intel_dp_mst_atomic_add_affected_crtcs(struct intel_atomic_state *state)
+{
+	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
+	struct intel_digital_connector_state *intel_conn_state;
+	struct drm_device *dev = state->base.dev;
+	struct intel_connector *intel_conn;
+	int i;
+
+	if (INTEL_GEN(dev_priv) < 12)
+		return 0;
+
+	for_each_new_intel_connector_in_state(state, intel_conn, intel_conn_state, i) {
+		struct drm_connector_list_iter conn_list_iter;
+		struct drm_connector *conn_iter;
+
+		if (!intel_conn->mst_port)
+			continue;
+
+		drm_connector_list_iter_begin(dev, &conn_list_iter);
+		drm_for_each_connector_iter(conn_iter, &conn_list_iter) {
+			struct drm_connector_state *conn_iter_state;
+			struct intel_connector *intel_conn_iter;
+			struct drm_crtc_state *crtc_state;
+
+			intel_conn_iter = to_intel_connector(conn_iter);
+
+			if (intel_conn_iter->mst_port != intel_conn->mst_port)
+				continue;
+
+			conn_iter_state = drm_atomic_get_connector_state(&state->base, conn_iter);
+			if (IS_ERR(conn_iter_state)) {
+				drm_connector_list_iter_end(&conn_list_iter);
+				return PTR_ERR(conn_iter_state);
+			}
+			if (!conn_iter_state->crtc)
+				continue;
+
+			crtc_state = drm_atomic_get_crtc_state(&state->base,
+							       conn_iter_state->crtc);
+			if (IS_ERR(crtc_state)) {
+				drm_connector_list_iter_end(&conn_list_iter);
+				return PTR_ERR(crtc_state);
+			}
+		}
+		drm_connector_list_iter_end(&conn_list_iter);
+	}
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.h b/drivers/gpu/drm/i915/display/intel_dp_mst.h
index f660ad80db04..173598aa81d2 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.h
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.h
@@ -6,10 +6,12 @@ 
 #ifndef __INTEL_DP_MST_H__
 #define __INTEL_DP_MST_H__
 
+struct intel_atomic_state;
 struct intel_digital_port;
 
 int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
 void intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port);
+int intel_dp_mst_atomic_add_affected_crtcs(struct intel_atomic_state *state);
 int intel_dp_mst_encoder_active_links(struct intel_digital_port *intel_dig_port);
 
 #endif /* __INTEL_DP_MST_H__ */
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 045d421e9a7a..a55f15eb6175 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -9419,6 +9419,9 @@  enum skl_power_gate {
 #define  TRANS_DDI_EDP_INPUT_A_ONOFF	(4 << 12)
 #define  TRANS_DDI_EDP_INPUT_B_ONOFF	(5 << 12)
 #define  TRANS_DDI_EDP_INPUT_C_ONOFF	(6 << 12)
+#define  TRANS_DDI_MST_TRANSPORT_SELECT_SHIFT		10 /* TGL+ */
+#define  TRANS_DDI_MST_TRANSPORT_SELECT_MASK		(0x3 << 10)
+#define  TRANS_DDI_MST_TRANSPORT_SELECT_DPTP(trans)	((trans) << 10)
 #define  TRANS_DDI_HDCP_SIGNALLING	(1 << 9)
 #define  TRANS_DDI_DP_VC_PAYLOAD_ALLOC	(1 << 8)
 #define  TRANS_DDI_HDMI_SCRAMBLER_CTS_ENABLE (1 << 7)

Comments

On Sat, 17 Aug 2019, Lucas De Marchi <lucas.demarchi@intel.com> wrote:
> From: José Roberto de Souza <jose.souza@intel.com>
>
> On TGL the blending of all the streams have moved from DDI to
> transcoder, so now every transcoder working over the same MST port must
> send its stream to a master transcoder and master will send to DDI
> respecting the time slots.
>
> So here it is picking the lowest pipe/transcoder as it will be
> enabled first and disabled last.
> BSpec: 50493
> BSpec: 49190
>
> v2: Missed set mst_master_trans to TRANSCODER_INVALID when computing HSW
>     encoder config. HSW CRT hw state readout calls
>     hsw_crt_get_config()->intel_ddi_get_config() that will set
>     mst_master_trans to TRANSCODER_INVALID causing the mismatch when
>     verifying CRTC state after a modeset. (José)
>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Manasi Navare <manasi.d.navare@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_crt.c      |   2 +
>  drivers/gpu/drm/i915/display/intel_ddi.c      |  17 ++
>  drivers/gpu/drm/i915/display/intel_display.c  |  15 ++
>  drivers/gpu/drm/i915/display/intel_display.h  |   3 +
>  .../drm/i915/display/intel_display_types.h    |   3 +
>  drivers/gpu/drm/i915/display/intel_dp_mst.c   | 159 +++++++++++++++++-
>  drivers/gpu/drm/i915/display/intel_dp_mst.h   |   2 +
>  drivers/gpu/drm/i915/i915_reg.h               |   3 +
>  8 files changed, 201 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_crt.c b/drivers/gpu/drm/i915/display/intel_crt.c
> index e6e8d4a82044..503135200cb3 100644
> --- a/drivers/gpu/drm/i915/display/intel_crt.c
> +++ b/drivers/gpu/drm/i915/display/intel_crt.c
> @@ -416,6 +416,8 @@ static int hsw_crt_compute_config(struct intel_encoder *encoder,
>  	/* FDI must always be 2.7 GHz */
>  	pipe_config->port_clock = 135000 * 2;
>  
> +	pipe_config->mst_master_trans = TRANSCODER_INVALID;
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 1f591e69b742..50a26bea8cde 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -1840,6 +1840,12 @@ void intel_ddi_enable_transcoder_func(const struct intel_crtc_state *crtc_state)
>  	} else if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST)) {
>  		temp |= TRANS_DDI_MODE_SELECT_DP_MST;
>  		temp |= DDI_PORT_WIDTH(crtc_state->lane_count);
> +
> +		if (INTEL_GEN(dev_priv) >= 12) {
> +			enum transcoder master = crtc_state->mst_master_trans;
> +
> +			temp |= TRANS_DDI_MST_TRANSPORT_SELECT_DPTP(master);

For some reason I'd feel safer if we had a WARN_ON(master ==
TRANSCODER_INVALID) somewhere around here.


> +		}
>  	} else {
>  		temp |= TRANS_DDI_MODE_SELECT_DP_SST;
>  		temp |= DDI_PORT_WIDTH(crtc_state->lane_count);
> @@ -3861,6 +3867,8 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
>  		break;
>  	}
>  
> +	pipe_config->mst_master_trans = TRANSCODER_INVALID;
> +
>  	switch (temp & TRANS_DDI_MODE_SELECT_MASK) {
>  	case TRANS_DDI_MODE_SELECT_HDMI:
>  		pipe_config->has_hdmi_sink = true;
> @@ -3896,6 +3904,13 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
>  		pipe_config->output_types |= BIT(INTEL_OUTPUT_DP_MST);
>  		pipe_config->lane_count =
>  			((temp & DDI_PORT_WIDTH_MASK) >> DDI_PORT_WIDTH_SHIFT) + 1;
> +
> +		if (INTEL_GEN(dev_priv) >= 12) {
> +			temp = temp & TRANS_DDI_MST_TRANSPORT_SELECT_MASK;
> +			temp = temp >> TRANS_DDI_MST_TRANSPORT_SELECT_SHIFT;
> +			pipe_config->mst_master_trans = temp;
> +		}
> +
>  		intel_dp_get_m_n(intel_crtc, pipe_config);
>  		break;
>  	default:
> @@ -3998,6 +4013,8 @@ static int intel_ddi_compute_config(struct intel_encoder *encoder,
>  
>  	intel_ddi_compute_min_voltage_level(dev_priv, pipe_config);
>  
> +	pipe_config->mst_master_trans = TRANSCODER_INVALID;
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index ddb8436e2208..109d4fd961c6 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -47,6 +47,7 @@
>  #include "display/intel_crt.h"
>  #include "display/intel_ddi.h"
>  #include "display/intel_dp.h"
> +#include "display/intel_dp_mst.h"
>  #include "display/intel_dsi.h"
>  #include "display/intel_dvo.h"
>  #include "display/intel_gmbus.h"
> @@ -12138,6 +12139,14 @@ static void intel_dump_pipe_config(const struct intel_crtc_state *pipe_config,
>  
>  	intel_dpll_dump_hw_state(dev_priv, &pipe_config->dpll_hw_state);
>  
> +	if (INTEL_GEN(dev_priv) >= 12 &&
> +	    intel_crtc_has_type(pipe_config, INTEL_OUTPUT_DP_MST)) {
> +		enum transcoder master = pipe_config->mst_master_trans;
> +
> +		DRM_DEBUG_KMS("master mst cpu_transcoder: %s\n",
> +			      transcoder_name(master));
> +	}
> +
>  dump_planes:
>  	if (!state)
>  		return;
> @@ -12821,6 +12830,8 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
>  	PIPE_CONF_CHECK_INFOFRAME(hdmi);
>  	PIPE_CONF_CHECK_INFOFRAME(drm);
>  
> +	PIPE_CONF_CHECK_I(mst_master_trans);

This is actually more subtle than it looks. We now check it for all
platforms and MST and non-MST alike. Which means non-MST and pre gen 12
must set it to TRANSCODER_INVALID on compute config *and* readout.

I think I'll let it slide here, but I think we need to consider this and
decide whether we want this in general. Indeed TRANSCODER_INVALID is
created just for this, and it is actually not really used as a value
anywhere except here, but generates worry all over the place, "what if
this is -1".

Perhaps in general I'd like the approach of only doing the readout when
it's relevant, and only checking the value when it's relevant.

BR,
Jani.


> +
>  #undef PIPE_CONF_CHECK_X
>  #undef PIPE_CONF_CHECK_I
>  #undef PIPE_CONF_CHECK_BOOL
> @@ -13597,6 +13608,10 @@ static int intel_atomic_check(struct drm_device *dev,
>  	int ret, i;
>  	bool any_ms = state->cdclk.force_min_cdclk_changed;
>  
> +	ret = intel_dp_mst_atomic_add_affected_crtcs(state);
> +	if (ret)
> +		return ret;
> +
>  	/* Catch I915_MODE_FLAG_INHERITED */
>  	for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
>  					    new_crtc_state, i) {
> diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h
> index b63fb7a4599e..282e8d8f1cc1 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.h
> +++ b/drivers/gpu/drm/i915/display/intel_display.h
> @@ -91,6 +91,8 @@ enum pipe {
>  #define pipe_name(p) ((p) + 'A')
>  
>  enum transcoder {
> +	TRANSCODER_INVALID = -1,
> +
>  	/*
>  	 * The following transcoders have a 1:1 transcoder -> pipe mapping,
>  	 * keep their values fixed: the code assumes that TRANSCODER_A=0, the
> @@ -132,6 +134,7 @@ static inline const char *transcoder_name(enum transcoder transcoder)
>  		return "DSI A";
>  	case TRANSCODER_DSI_C:
>  		return "DSI C";
> +	case TRANSCODER_INVALID:
>  	default:
>  		return "<invalid>";
>  	}
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 3c1a5f3e1d22..b7da955954b7 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -984,6 +984,9 @@ struct intel_crtc_state {
>  
>  	/* Forward Error correction State */
>  	bool fec_enable;
> +
> +	/* Master transcoder for all streams, only used on TGL+ */
> +	enum transcoder mst_master_trans;
>  };
>  
>  struct intel_crtc {
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index f52cdd4ca877..670a12fd2f27 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -87,6 +87,50 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
>  	return 0;
>  }
>  
> +/*
> + * Iterate over all the CRTCs and return the transcoder of the lowest CRTC that
> + * share the same MST connector.
> + */
> +static enum transcoder
> +mst_compute_master_trans(struct drm_atomic_state *state,
> +			 struct drm_connector *mst_conn)
> +{
> +	struct intel_connector *intel_mst_conn = to_intel_connector(mst_conn);
> +	struct intel_atomic_state *intel_state = to_intel_atomic_state(state);
> +	struct drm_i915_private *dev_priv = to_i915(state->dev);
> +	struct intel_crtc_state *intel_crtc_state;
> +	struct intel_crtc *intel_crtc;
> +	int i;
> +
> +	if (INTEL_GEN(dev_priv) < 12)
> +		return TRANSCODER_INVALID;
> +
> +	/* Iterate from the lowest to the highest pipe */
> +	for_each_new_intel_crtc_in_state(intel_state, intel_crtc, intel_crtc_state, i) {
> +		struct intel_digital_connector_state *intel_conn_state;
> +		struct intel_connector *intel_conn;
> +		int j;
> +
> +		if (!intel_crtc_state->base.active)
> +			continue;
> +
> +		for_each_new_intel_connector_in_state(intel_state, intel_conn,
> +						      intel_conn_state, j) {
> +			/* Only care about connectors of this CRTC */
> +			if (intel_conn_state->base.crtc !=
> +			    intel_crtc_state->base.crtc)
> +				continue;
> +
> +			if (intel_conn->mst_port != intel_mst_conn->mst_port)
> +				continue;
> +
> +			return intel_crtc_state->cpu_transcoder;
> +		}
> +	}
> +
> +	return TRANSCODER_INVALID;
> +}
> +
>  static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
>  				       struct intel_crtc_state *pipe_config,
>  				       struct drm_connector_state *conn_state)
> @@ -94,14 +138,15 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>  	struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
>  	struct intel_dp *intel_dp = &intel_mst->primary->dp;
> -	struct intel_connector *connector =
> -		to_intel_connector(conn_state->connector);
> +	struct drm_connector *connector = conn_state->connector;
> +	struct intel_connector *intel_connector = to_intel_connector(connector);
>  	struct intel_digital_connector_state *intel_conn_state =
>  		to_intel_digital_connector_state(conn_state);
>  	const struct drm_display_mode *adjusted_mode =
>  		&pipe_config->base.adjusted_mode;
> -	void *port = connector->port;
> +	void *port = intel_connector->port;
>  	struct link_config_limits limits;
> +	enum transcoder master;
>  	int ret;
>  
>  	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
> @@ -146,6 +191,51 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
>  
>  	intel_ddi_compute_min_voltage_level(dev_priv, pipe_config);
>  
> +	master = mst_compute_master_trans(conn_state->state, connector);
> +	pipe_config->mst_master_trans = master;
> +
> +	return 0;
> +}
> +
> +static int
> +intel_dp_mst_master_trans_check(struct drm_connector *conn,
> +				struct drm_connector_state *new_conn_state)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(conn->dev);
> +	struct drm_atomic_state *state = new_conn_state->state;
> +	struct drm_connector_state *old_conn_state =
> +		drm_atomic_get_old_connector_state(state, conn);
> +	struct drm_crtc *new_crtc = new_conn_state->crtc;
> +	struct drm_crtc *old_crtc = old_conn_state->crtc;
> +	enum transcoder old_master_trans = TRANSCODER_INVALID;
> +	enum transcoder new_master_trans = TRANSCODER_INVALID;
> +	struct drm_crtc_state *new_crtc_state, *old_crtc_state;
> +
> +	if (INTEL_GEN(dev_priv) < 12)
> +		return 0;
> +
> +	if (old_crtc) {
> +		struct intel_crtc_state *intel_crtc_state;
> +
> +		old_crtc_state = drm_atomic_get_new_crtc_state(state, old_crtc);
> +		intel_crtc_state = to_intel_crtc_state(old_crtc_state);
> +		old_master_trans = intel_crtc_state->mst_master_trans;
> +	}
> +
> +	if (new_crtc) {
> +		struct intel_crtc_state *intel_crtc_state;
> +
> +		new_crtc_state = drm_atomic_get_new_crtc_state(state, new_crtc);
> +		intel_crtc_state = to_intel_crtc_state(new_crtc_state);
> +		new_master_trans = mst_compute_master_trans(state, conn);
> +	}
> +
> +	if (old_crtc && old_master_trans != new_master_trans)
> +		old_crtc_state->mode_changed = true;
> +
> +	if (new_crtc && old_master_trans != new_master_trans)
> +		new_crtc_state->mode_changed = true;
> +
>  	return 0;
>  }
>  
> @@ -168,6 +258,10 @@ intel_dp_mst_atomic_check(struct drm_connector *connector,
>  	if (ret)
>  		return ret;
>  
> +	ret = intel_dp_mst_master_trans_check(connector, new_conn_state);
> +	if (ret)
> +		return ret;
> +
>  	if (!old_conn_state->crtc)
>  		return 0;
>  
> @@ -666,3 +760,62 @@ intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port)
>  	drm_dp_mst_topology_mgr_destroy(&intel_dp->mst_mgr);
>  	/* encoders will get killed by normal cleanup */
>  }
> +
> +/**
> + * intel_dp_mst_atomic_add_affected_crtcs - Add all CRTCs that share the MST
> + * stream with the CRTCs in the current atomic state.
> + * @state: state to add CRTCs
> + *
> + * It is needed add the CRTCs trigger a call to atomic_check() to
> + * every connector attached to the CRTC in case a new master transcoder will
> + * be needed.
> + */
> +int intel_dp_mst_atomic_add_affected_crtcs(struct intel_atomic_state *state)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
> +	struct intel_digital_connector_state *intel_conn_state;
> +	struct drm_device *dev = state->base.dev;
> +	struct intel_connector *intel_conn;
> +	int i;
> +
> +	if (INTEL_GEN(dev_priv) < 12)
> +		return 0;
> +
> +	for_each_new_intel_connector_in_state(state, intel_conn, intel_conn_state, i) {
> +		struct drm_connector_list_iter conn_list_iter;
> +		struct drm_connector *conn_iter;
> +
> +		if (!intel_conn->mst_port)
> +			continue;
> +
> +		drm_connector_list_iter_begin(dev, &conn_list_iter);
> +		drm_for_each_connector_iter(conn_iter, &conn_list_iter) {
> +			struct drm_connector_state *conn_iter_state;
> +			struct intel_connector *intel_conn_iter;
> +			struct drm_crtc_state *crtc_state;
> +
> +			intel_conn_iter = to_intel_connector(conn_iter);
> +
> +			if (intel_conn_iter->mst_port != intel_conn->mst_port)
> +				continue;
> +
> +			conn_iter_state = drm_atomic_get_connector_state(&state->base, conn_iter);
> +			if (IS_ERR(conn_iter_state)) {
> +				drm_connector_list_iter_end(&conn_list_iter);
> +				return PTR_ERR(conn_iter_state);
> +			}
> +			if (!conn_iter_state->crtc)
> +				continue;
> +
> +			crtc_state = drm_atomic_get_crtc_state(&state->base,
> +							       conn_iter_state->crtc);
> +			if (IS_ERR(crtc_state)) {
> +				drm_connector_list_iter_end(&conn_list_iter);
> +				return PTR_ERR(crtc_state);
> +			}
> +		}
> +		drm_connector_list_iter_end(&conn_list_iter);
> +	}
> +
> +	return 0;
> +}
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.h b/drivers/gpu/drm/i915/display/intel_dp_mst.h
> index f660ad80db04..173598aa81d2 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.h
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.h
> @@ -6,10 +6,12 @@
>  #ifndef __INTEL_DP_MST_H__
>  #define __INTEL_DP_MST_H__
>  
> +struct intel_atomic_state;
>  struct intel_digital_port;
>  
>  int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
>  void intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port);
> +int intel_dp_mst_atomic_add_affected_crtcs(struct intel_atomic_state *state);
>  int intel_dp_mst_encoder_active_links(struct intel_digital_port *intel_dig_port);
>  
>  #endif /* __INTEL_DP_MST_H__ */
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 045d421e9a7a..a55f15eb6175 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -9419,6 +9419,9 @@ enum skl_power_gate {
>  #define  TRANS_DDI_EDP_INPUT_A_ONOFF	(4 << 12)
>  #define  TRANS_DDI_EDP_INPUT_B_ONOFF	(5 << 12)
>  #define  TRANS_DDI_EDP_INPUT_C_ONOFF	(6 << 12)
> +#define  TRANS_DDI_MST_TRANSPORT_SELECT_SHIFT		10 /* TGL+ */
> +#define  TRANS_DDI_MST_TRANSPORT_SELECT_MASK		(0x3 << 10)
> +#define  TRANS_DDI_MST_TRANSPORT_SELECT_DPTP(trans)	((trans) << 10)
>  #define  TRANS_DDI_HDCP_SIGNALLING	(1 << 9)
>  #define  TRANS_DDI_DP_VC_PAYLOAD_ALLOC	(1 << 8)
>  #define  TRANS_DDI_HDMI_SCRAMBLER_CTS_ENABLE (1 << 7)
Op 17-08-2019 om 11:38 schreef Lucas De Marchi:
> From: José Roberto de Souza <jose.souza@intel.com>
>
> On TGL the blending of all the streams have moved from DDI to
> transcoder, so now every transcoder working over the same MST port must
> send its stream to a master transcoder and master will send to DDI
> respecting the time slots.
>
> So here it is picking the lowest pipe/transcoder as it will be
> enabled first and disabled last.
> BSpec: 50493
> BSpec: 49190
>
> v2: Missed set mst_master_trans to TRANSCODER_INVALID when computing HSW
>     encoder config. HSW CRT hw state readout calls
>     hsw_crt_get_config()->intel_ddi_get_config() that will set
>     mst_master_trans to TRANSCODER_INVALID causing the mismatch when
>     verifying CRTC state after a modeset. (José)
>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Manasi Navare <manasi.d.navare@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_crt.c      |   2 +
>  drivers/gpu/drm/i915/display/intel_ddi.c      |  17 ++
>  drivers/gpu/drm/i915/display/intel_display.c  |  15 ++
>  drivers/gpu/drm/i915/display/intel_display.h  |   3 +
>  .../drm/i915/display/intel_display_types.h    |   3 +
>  drivers/gpu/drm/i915/display/intel_dp_mst.c   | 159 +++++++++++++++++-
>  drivers/gpu/drm/i915/display/intel_dp_mst.h   |   2 +
>  drivers/gpu/drm/i915/i915_reg.h               |   3 +
>  8 files changed, 201 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_crt.c b/drivers/gpu/drm/i915/display/intel_crt.c
> index e6e8d4a82044..503135200cb3 100644
> --- a/drivers/gpu/drm/i915/display/intel_crt.c
> +++ b/drivers/gpu/drm/i915/display/intel_crt.c
> @@ -416,6 +416,8 @@ static int hsw_crt_compute_config(struct intel_encoder *encoder,
>  	/* FDI must always be 2.7 GHz */
>  	pipe_config->port_clock = 135000 * 2;
>  
> +	pipe_config->mst_master_trans = TRANSCODER_INVALID;
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 1f591e69b742..50a26bea8cde 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -1840,6 +1840,12 @@ void intel_ddi_enable_transcoder_func(const struct intel_crtc_state *crtc_state)
>  	} else if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST)) {
>  		temp |= TRANS_DDI_MODE_SELECT_DP_MST;
>  		temp |= DDI_PORT_WIDTH(crtc_state->lane_count);
> +
> +		if (INTEL_GEN(dev_priv) >= 12) {
> +			enum transcoder master = crtc_state->mst_master_trans;
> +
> +			temp |= TRANS_DDI_MST_TRANSPORT_SELECT_DPTP(master);
> +		}
>  	} else {
>  		temp |= TRANS_DDI_MODE_SELECT_DP_SST;
>  		temp |= DDI_PORT_WIDTH(crtc_state->lane_count);
> @@ -3861,6 +3867,8 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
>  		break;
>  	}
>  
> +	pipe_config->mst_master_trans = TRANSCODER_INVALID;
> +
>  	switch (temp & TRANS_DDI_MODE_SELECT_MASK) {
>  	case TRANS_DDI_MODE_SELECT_HDMI:
>  		pipe_config->has_hdmi_sink = true;
> @@ -3896,6 +3904,13 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
>  		pipe_config->output_types |= BIT(INTEL_OUTPUT_DP_MST);
>  		pipe_config->lane_count =
>  			((temp & DDI_PORT_WIDTH_MASK) >> DDI_PORT_WIDTH_SHIFT) + 1;
> +
> +		if (INTEL_GEN(dev_priv) >= 12) {
> +			temp = temp & TRANS_DDI_MST_TRANSPORT_SELECT_MASK;
> +			temp = temp >> TRANS_DDI_MST_TRANSPORT_SELECT_SHIFT;
> +			pipe_config->mst_master_trans = temp;
> +		}
> +
>  		intel_dp_get_m_n(intel_crtc, pipe_config);
>  		break;
>  	default:
> @@ -3998,6 +4013,8 @@ static int intel_ddi_compute_config(struct intel_encoder *encoder,
>  
>  	intel_ddi_compute_min_voltage_level(dev_priv, pipe_config);
>  
> +	pipe_config->mst_master_trans = TRANSCODER_INVALID;
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index ddb8436e2208..109d4fd961c6 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -47,6 +47,7 @@
>  #include "display/intel_crt.h"
>  #include "display/intel_ddi.h"
>  #include "display/intel_dp.h"
> +#include "display/intel_dp_mst.h"
>  #include "display/intel_dsi.h"
>  #include "display/intel_dvo.h"
>  #include "display/intel_gmbus.h"
> @@ -12138,6 +12139,14 @@ static void intel_dump_pipe_config(const struct intel_crtc_state *pipe_config,
>  
>  	intel_dpll_dump_hw_state(dev_priv, &pipe_config->dpll_hw_state);
>  
> +	if (INTEL_GEN(dev_priv) >= 12 &&
> +	    intel_crtc_has_type(pipe_config, INTEL_OUTPUT_DP_MST)) {
> +		enum transcoder master = pipe_config->mst_master_trans;
> +
> +		DRM_DEBUG_KMS("master mst cpu_transcoder: %s\n",
> +			      transcoder_name(master));
> +	}
> +
>  dump_planes:
>  	if (!state)
>  		return;
> @@ -12821,6 +12830,8 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
>  	PIPE_CONF_CHECK_INFOFRAME(hdmi);
>  	PIPE_CONF_CHECK_INFOFRAME(drm);
>  
> +	PIPE_CONF_CHECK_I(mst_master_trans);
> +
>  #undef PIPE_CONF_CHECK_X
>  #undef PIPE_CONF_CHECK_I
>  #undef PIPE_CONF_CHECK_BOOL
> @@ -13597,6 +13608,10 @@ static int intel_atomic_check(struct drm_device *dev,
>  	int ret, i;
>  	bool any_ms = state->cdclk.force_min_cdclk_changed;
>  
> +	ret = intel_dp_mst_atomic_add_affected_crtcs(state);
> +	if (ret)
> +		return ret;
> +
>  	/* Catch I915_MODE_FLAG_INHERITED */
>  	for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
>  					    new_crtc_state, i) {
> diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h
> index b63fb7a4599e..282e8d8f1cc1 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.h
> +++ b/drivers/gpu/drm/i915/display/intel_display.h
> @@ -91,6 +91,8 @@ enum pipe {
>  #define pipe_name(p) ((p) + 'A')
>  
>  enum transcoder {
> +	TRANSCODER_INVALID = -1,
> +
>  	/*
>  	 * The following transcoders have a 1:1 transcoder -> pipe mapping,
>  	 * keep their values fixed: the code assumes that TRANSCODER_A=0, the
> @@ -132,6 +134,7 @@ static inline const char *transcoder_name(enum transcoder transcoder)
>  		return "DSI A";
>  	case TRANSCODER_DSI_C:
>  		return "DSI C";
> +	case TRANSCODER_INVALID:
>  	default:
>  		return "<invalid>";
>  	}
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 3c1a5f3e1d22..b7da955954b7 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -984,6 +984,9 @@ struct intel_crtc_state {
>  
>  	/* Forward Error correction State */
>  	bool fec_enable;
> +
> +	/* Master transcoder for all streams, only used on TGL+ */
> +	enum transcoder mst_master_trans;
>  };
>  
>  struct intel_crtc {
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index f52cdd4ca877..670a12fd2f27 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -87,6 +87,50 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
>  	return 0;
>  }
>  
> +/*
> + * Iterate over all the CRTCs and return the transcoder of the lowest CRTC that
> + * share the same MST connector.
> + */
> +static enum transcoder
> +mst_compute_master_trans(struct drm_atomic_state *state,
> +			 struct drm_connector *mst_conn)
> +{
> +	struct intel_connector *intel_mst_conn = to_intel_connector(mst_conn);
> +	struct intel_atomic_state *intel_state = to_intel_atomic_state(state);
> +	struct drm_i915_private *dev_priv = to_i915(state->dev);
> +	struct intel_crtc_state *intel_crtc_state;
> +	struct intel_crtc *intel_crtc;
> +	int i;
> +
> +	if (INTEL_GEN(dev_priv) < 12)
> +		return TRANSCODER_INVALID;
> +
> +	/* Iterate from the lowest to the highest pipe */
> +	for_each_new_intel_crtc_in_state(intel_state, intel_crtc, intel_crtc_state, i) {
> +		struct intel_digital_connector_state *intel_conn_state;
> +		struct intel_connector *intel_conn;
> +		int j;
> +
> +		if (!intel_crtc_state->base.active)
> +			continue;
> +
> +		for_each_new_intel_connector_in_state(intel_state, intel_conn,
> +						      intel_conn_state, j) {
> +			/* Only care about connectors of this CRTC */
> +			if (intel_conn_state->base.crtc !=
> +			    intel_crtc_state->base.crtc)
> +				continue;
> +
> +			if (intel_conn->mst_port != intel_mst_conn->mst_port)
> +				continue;
> +
> +			return intel_crtc_state->cpu_transcoder;
> +		}
> +	}
> +
> +	return TRANSCODER_INVALID;
> +}
> +
>  static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
>  				       struct intel_crtc_state *pipe_config,
>  				       struct drm_connector_state *conn_state)
> @@ -94,14 +138,15 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>  	struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
>  	struct intel_dp *intel_dp = &intel_mst->primary->dp;
> -	struct intel_connector *connector =
> -		to_intel_connector(conn_state->connector);
> +	struct drm_connector *connector = conn_state->connector;
> +	struct intel_connector *intel_connector = to_intel_connector(connector);
>  	struct intel_digital_connector_state *intel_conn_state =
>  		to_intel_digital_connector_state(conn_state);
>  	const struct drm_display_mode *adjusted_mode =
>  		&pipe_config->base.adjusted_mode;
> -	void *port = connector->port;
> +	void *port = intel_connector->port;
>  	struct link_config_limits limits;
> +	enum transcoder master;
>  	int ret;
>  
>  	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
> @@ -146,6 +191,51 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
>  
>  	intel_ddi_compute_min_voltage_level(dev_priv, pipe_config);
>  
> +	master = mst_compute_master_trans(conn_state->state, connector);
> +	pipe_config->mst_master_trans = master;
> +
> +	return 0;
> +}
> +
> +static int
> +intel_dp_mst_master_trans_check(struct drm_connector *conn,
> +				struct drm_connector_state *new_conn_state)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(conn->dev);
> +	struct drm_atomic_state *state = new_conn_state->state;
> +	struct drm_connector_state *old_conn_state =
> +		drm_atomic_get_old_connector_state(state, conn);
> +	struct drm_crtc *new_crtc = new_conn_state->crtc;
> +	struct drm_crtc *old_crtc = old_conn_state->crtc;
> +	enum transcoder old_master_trans = TRANSCODER_INVALID;
> +	enum transcoder new_master_trans = TRANSCODER_INVALID;
> +	struct drm_crtc_state *new_crtc_state, *old_crtc_state;
> +
> +	if (INTEL_GEN(dev_priv) < 12)
> +		return 0;
> +
> +	if (old_crtc) {
> +		struct intel_crtc_state *intel_crtc_state;
> +
> +		old_crtc_state = drm_atomic_get_new_crtc_state(state, old_crtc);
> +		intel_crtc_state = to_intel_crtc_state(old_crtc_state);
> +		old_master_trans = intel_crtc_state->mst_master_trans;
> +	}
> +
> +	if (new_crtc) {
> +		struct intel_crtc_state *intel_crtc_state;
> +
> +		new_crtc_state = drm_atomic_get_new_crtc_state(state, new_crtc);
> +		intel_crtc_state = to_intel_crtc_state(new_crtc_state);
> +		new_master_trans = mst_compute_master_trans(state, conn);
> +	}
> +
> +	if (old_crtc && old_master_trans != new_master_trans)
> +		old_crtc_state->mode_changed = true;
> +
> +	if (new_crtc && old_master_trans != new_master_trans)
> +		new_crtc_state->mode_changed = true;
> +
>  	return 0;
>  }
>  
> @@ -168,6 +258,10 @@ intel_dp_mst_atomic_check(struct drm_connector *connector,
>  	if (ret)
>  		return ret;
>  
> +	ret = intel_dp_mst_master_trans_check(connector, new_conn_state);
> +	if (ret)
> +		return ret;
> +
>  	if (!old_conn_state->crtc)
>  		return 0;
>  
> @@ -666,3 +760,62 @@ intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port)
>  	drm_dp_mst_topology_mgr_destroy(&intel_dp->mst_mgr);
>  	/* encoders will get killed by normal cleanup */
>  }
> +
> +/**
> + * intel_dp_mst_atomic_add_affected_crtcs - Add all CRTCs that share the MST
> + * stream with the CRTCs in the current atomic state.
> + * @state: state to add CRTCs
> + *
> + * It is needed add the CRTCs trigger a call to atomic_check() to
> + * every connector attached to the CRTC in case a new master transcoder will
> + * be needed.
> + */
> +int intel_dp_mst_atomic_add_affected_crtcs(struct intel_atomic_state *state)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
> +	struct intel_digital_connector_state *intel_conn_state;
> +	struct drm_device *dev = state->base.dev;
> +	struct intel_connector *intel_conn;
> +	int i;
> +
> +	if (INTEL_GEN(dev_priv) < 12)
> +		return 0;
> +
> +	for_each_new_intel_connector_in_state(state, intel_conn, intel_conn_state, i) {
> +		struct drm_connector_list_iter conn_list_iter;
> +		struct drm_connector *conn_iter;
> +
> +		if (!intel_conn->mst_port)
> +			continue;
> +
> +		drm_connector_list_iter_begin(dev, &conn_list_iter);
> +		drm_for_each_connector_iter(conn_iter, &conn_list_iter) {
> +			struct drm_connector_state *conn_iter_state;
> +			struct intel_connector *intel_conn_iter;
> +			struct drm_crtc_state *crtc_state;
> +
> +			intel_conn_iter = to_intel_connector(conn_iter);
> +
> +			if (intel_conn_iter->mst_port != intel_conn->mst_port)
> +				continue;
> +
> +			conn_iter_state = drm_atomic_get_connector_state(&state->base, conn_iter);
> +			if (IS_ERR(conn_iter_state)) {
> +				drm_connector_list_iter_end(&conn_list_iter);
> +				return PTR_ERR(conn_iter_state);
> +			}
> +			if (!conn_iter_state->crtc)
> +				continue;
> +
> +			crtc_state = drm_atomic_get_crtc_state(&state->base,
> +							       conn_iter_state->crtc);
> +			if (IS_ERR(crtc_state)) {
> +				drm_connector_list_iter_end(&conn_list_iter);
> +				return PTR_ERR(crtc_state);
> +			}
> +		}
> +		drm_connector_list_iter_end(&conn_list_iter);
> +	}
> +
> +	return 0;
> +}

Looks sane.

Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.h b/drivers/gpu/drm/i915/display/intel_dp_mst.h
> index f660ad80db04..173598aa81d2 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.h
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.h
> @@ -6,10 +6,12 @@
>  #ifndef __INTEL_DP_MST_H__
>  #define __INTEL_DP_MST_H__
>  
> +struct intel_atomic_state;
>  struct intel_digital_port;
>  
>  int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
>  void intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port);
> +int intel_dp_mst_atomic_add_affected_crtcs(struct intel_atomic_state *state);
>  int intel_dp_mst_encoder_active_links(struct intel_digital_port *intel_dig_port);
>  
>  #endif /* __INTEL_DP_MST_H__ */
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 045d421e9a7a..a55f15eb6175 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -9419,6 +9419,9 @@ enum skl_power_gate {
>  #define  TRANS_DDI_EDP_INPUT_A_ONOFF	(4 << 12)
>  #define  TRANS_DDI_EDP_INPUT_B_ONOFF	(5 << 12)
>  #define  TRANS_DDI_EDP_INPUT_C_ONOFF	(6 << 12)
> +#define  TRANS_DDI_MST_TRANSPORT_SELECT_SHIFT		10 /* TGL+ */
> +#define  TRANS_DDI_MST_TRANSPORT_SELECT_MASK		(0x3 << 10)
> +#define  TRANS_DDI_MST_TRANSPORT_SELECT_DPTP(trans)	((trans) << 10)
>  #define  TRANS_DDI_HDCP_SIGNALLING	(1 << 9)
>  #define  TRANS_DDI_DP_VC_PAYLOAD_ALLOC	(1 << 8)
>  #define  TRANS_DDI_HDMI_SCRAMBLER_CTS_ENABLE (1 << 7)