diff --git a/drivers/gpu/drm/i915/display/intel_atomic.c b/drivers/gpu/drm/i915/display/intel_atomic.c
index d0b5414127df..580244abf62d 100644
--- a/drivers/gpu/drm/i915/display/intel_atomic.c
+++ b/drivers/gpu/drm/i915/display/intel_atomic.c
@@ -198,6 +198,26 @@ intel_connector_needs_modeset(struct intel_atomic_state *state,
 									    new_conn_state->crtc)));
 }
 
+/**
+ * intel_any_crtc_needs_modeset - check if any CRTC needs a modeset
+ * @state: the atomic state corresponding to this modeset
+ *
+ * Returns true if any CRTC in @state needs a modeset.
+ */
+bool intel_any_crtc_needs_modeset(struct intel_atomic_state *state)
+{
+	struct intel_crtc *crtc;
+	struct intel_crtc_state *crtc_state;
+	int i;
+
+	for_each_new_intel_crtc_in_state(state, crtc, crtc_state, i) {
+		if (intel_crtc_needs_modeset(crtc_state))
+			return true;
+	}
+
+	return false;
+}
+
 struct intel_digital_connector_state *
 intel_atomic_get_digital_connector_state(struct intel_atomic_state *state,
 					 struct intel_connector *connector)
diff --git a/drivers/gpu/drm/i915/display/intel_atomic.h b/drivers/gpu/drm/i915/display/intel_atomic.h
index 62a3365ed5e6..d2700c74c9da 100644
--- a/drivers/gpu/drm/i915/display/intel_atomic.h
+++ b/drivers/gpu/drm/i915/display/intel_atomic.h
@@ -35,6 +35,7 @@ struct drm_connector_state *
 intel_digital_connector_duplicate_state(struct drm_connector *connector);
 bool intel_connector_needs_modeset(struct intel_atomic_state *state,
 				   struct drm_connector *connector);
+bool intel_any_crtc_needs_modeset(struct intel_atomic_state *state);
 struct intel_digital_connector_state *
 intel_atomic_get_digital_connector_state(struct intel_atomic_state *state,
 					 struct intel_connector *connector);
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index cbad75deadd0..d779c1c38a41 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -10456,6 +10456,9 @@ static int intel_atomic_check(struct drm_device *dev,
 	if (ret)
 		goto fail;
 
+	if (intel_any_crtc_needs_modeset(state))
+		any_ms = true;
+
 	if (any_ms) {
 		ret = intel_modeset_checks(state);
 		if (ret)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 70b097ddae28..a447f3882bd7 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2929,6 +2929,15 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
 #define MBUS_BBOX_CTL_S1		_MMIO(0x45040)
 #define MBUS_BBOX_CTL_S2		_MMIO(0x45044)
 
+#define MBUS_CTL			_MMIO(0x4438C)
+#define MBUS_JOIN			REG_BIT(31)
+#define MBUS_HASHING_MODE_MASK		REG_BIT(30)
+#define MBUS_HASHING_MODE_2x2		REG_FIELD_PREP(MBUS_HASHING_MODE_MASK, 0)
+#define MBUS_HASHING_MODE_1x4		REG_FIELD_PREP(MBUS_HASHING_MODE_MASK, 1)
+#define MBUS_JOIN_PIPE_SELECT_MASK	REG_GENMASK(28, 26)
+#define MBUS_JOIN_PIPE_SELECT(pipe)	REG_FIELD_PREP(MBUS_JOIN_PIPE_SELECT_MASK, pipe)
+#define MBUS_JOIN_PIPE_SELECT_NONE	MBUS_JOIN_PIPE_SELECT(7)
+
 #define HDPORT_STATE			_MMIO(0x45050)
 #define   HDPORT_DPLL_USED_MASK		REG_GENMASK(15, 12)
 #define   HDPORT_DDI_USED(phy)		REG_BIT(2 * (phy) + 1)
@@ -8136,6 +8145,8 @@ enum {
 #define  DBUF_POWER_STATE			REG_BIT(30)
 #define  DBUF_TRACKER_STATE_SERVICE_MASK	REG_GENMASK(23, 19)
 #define  DBUF_TRACKER_STATE_SERVICE(x)		REG_FIELD_PREP(DBUF_TRACKER_STATE_SERVICE_MASK, x)
+#define  DBUF_MIN_TRACKER_STATE_SERVICE_MASK	REG_GENMASK(18, 16) /* ADL-P+ */
+#define  DBUF_MIN_TRACKER_STATE_SERVICE(x)		REG_FIELD_PREP(DBUF_MIN_TRACKER_STATE_SERVICE_MASK, x) /* ADL-P+ */
 
 #define GEN7_MSG_CTL	_MMIO(0x45010)
 #define  WAIT_FOR_PCH_RESET_ACK		(1 << 1)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index e9a8fb1773f3..7fae920fa6ae 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4269,7 +4269,6 @@ skl_cursor_allocation(const struct intel_crtc_state *crtc_state,
 static void skl_ddb_entry_init_from_hw(struct drm_i915_private *dev_priv,
 				       struct skl_ddb_entry *entry, u32 reg)
 {
-
 	entry->start = reg & DDB_ENTRY_MASK;
 	entry->end = (reg >> DDB_ENTRY_END_SHIFT) & DDB_ENTRY_MASK;
 
@@ -4394,6 +4393,7 @@ skl_plane_downscale_amount(const struct intel_crtc_state *crtc_state,
 struct dbuf_slice_conf_entry {
 	u8 active_pipes;
 	u8 dbuf_mask[I915_MAX_PIPES];
+	bool join_mbus;
 };
 
 /*
@@ -4586,14 +4586,16 @@ static const struct dbuf_slice_conf_entry adlp_allowed_dbufs[] = {
 	{
 		.active_pipes = BIT(PIPE_A),
 		.dbuf_mask = {
-			[PIPE_A] = BIT(DBUF_S1) | BIT(DBUF_S2),
+			[PIPE_A] = BIT(DBUF_S1) | BIT(DBUF_S2) | BIT(DBUF_S3) | BIT(DBUF_S4),
 		},
+		.join_mbus = true,
 	},
 	{
 		.active_pipes = BIT(PIPE_B),
 		.dbuf_mask = {
-			[PIPE_B] = BIT(DBUF_S3) | BIT(DBUF_S4),
+			[PIPE_B] = BIT(DBUF_S1) | BIT(DBUF_S2) | BIT(DBUF_S3) | BIT(DBUF_S4),
 		},
+		.join_mbus = true,
 	},
 	{
 		.active_pipes = BIT(PIPE_A) | BIT(PIPE_B),
@@ -4694,6 +4696,23 @@ static const struct dbuf_slice_conf_entry adlp_allowed_dbufs[] = {
 
 };
 
+static bool check_mbus_joined(u8 active_pipes,
+			      const struct dbuf_slice_conf_entry *dbuf_slices)
+{
+	int i;
+
+	for (i = 0; i < dbuf_slices[i].active_pipes; i++) {
+		if (dbuf_slices[i].active_pipes == active_pipes)
+			return dbuf_slices[i].join_mbus;
+	}
+	return false;
+}
+
+static bool adlp_check_mbus_joined(u8 active_pipes)
+{
+	return check_mbus_joined(active_pipes, adlp_allowed_dbufs);
+}
+
 static u8 compute_dbuf_slices(enum pipe pipe, u8 active_pipes,
 			      const struct dbuf_slice_conf_entry *dbuf_slices)
 {
@@ -5967,16 +5986,29 @@ skl_compute_ddb(struct intel_atomic_state *state)
 
 	new_dbuf_state->enabled_slices = intel_dbuf_enabled_slices(new_dbuf_state);
 
-	if (old_dbuf_state->enabled_slices != new_dbuf_state->enabled_slices) {
+	if (IS_ALDERLAKE_P(dev_priv))
+		new_dbuf_state->joined_mbus = adlp_check_mbus_joined(new_dbuf_state->active_pipes);
+
+	if (old_dbuf_state->enabled_slices != new_dbuf_state->enabled_slices ||
+	    old_dbuf_state->joined_mbus != new_dbuf_state->joined_mbus) {
 		ret = intel_atomic_serialize_global_state(&new_dbuf_state->base);
 		if (ret)
 			return ret;
 
+		if (old_dbuf_state->joined_mbus != new_dbuf_state->joined_mbus) {
+			/* TODO: Implement vblank synchronized MBUS joining changes */
+			ret = intel_modeset_all_pipes(state);
+			if (ret)
+				return ret;
+		}
+
 		drm_dbg_kms(&dev_priv->drm,
-			    "Enabled dbuf slices 0x%x -> 0x%x (out of %d dbuf slices)\n",
+			    "Enabled dbuf slices 0x%x -> 0x%x (out of %d dbuf slices), mbus joined? %s->%s\n",
 			    old_dbuf_state->enabled_slices,
 			    new_dbuf_state->enabled_slices,
-			    INTEL_INFO(dev_priv)->num_supported_dbuf_slices);
+			    INTEL_INFO(dev_priv)->num_supported_dbuf_slices,
+			    yesno(old_dbuf_state->joined_mbus),
+			    yesno(new_dbuf_state->joined_mbus));
 	}
 
 	for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i) {
@@ -6429,6 +6461,9 @@ void skl_wm_get_hw_state(struct drm_i915_private *dev_priv)
 		to_intel_dbuf_state(dev_priv->dbuf.obj.state);
 	struct intel_crtc *crtc;
 
+	if (IS_ALDERLAKE_P(dev_priv))
+		dbuf_state->joined_mbus = intel_de_read(dev_priv, MBUS_CTL) & MBUS_JOIN;
+
 	for_each_intel_crtc(&dev_priv->drm, crtc) {
 		struct intel_crtc_state *crtc_state =
 			to_intel_crtc_state(crtc->base.state);
@@ -6468,10 +6503,11 @@ void skl_wm_get_hw_state(struct drm_i915_private *dev_priv)
 		crtc_state->wm.skl.ddb.end = mbus_offset + dbuf_state->ddb[pipe].end;
 
 		drm_dbg_kms(&dev_priv->drm,
-			    "[CRTC:%d:%s] dbuf slices 0x%x, ddb (%d - %d), active pipes 0x%x\n",
+			    "[CRTC:%d:%s] dbuf slices 0x%x, ddb (%d - %d), active pipes 0x%x, mbus joined: %s\n",
 			    crtc->base.base.id, crtc->base.name,
 			    dbuf_state->slices[pipe], dbuf_state->ddb[pipe].start,
-			    dbuf_state->ddb[pipe].end, dbuf_state->active_pipes);
+			    dbuf_state->ddb[pipe].end, dbuf_state->active_pipes,
+			    yesno(dbuf_state->joined_mbus));
 	}
 
 	dbuf_state->enabled_slices = dev_priv->dbuf.enabled_slices;
@@ -7976,6 +8012,46 @@ int intel_dbuf_init(struct drm_i915_private *dev_priv)
 	return 0;
 }
 
+/*
+ * Configure MBUS_CTL and all DBUF_CTL_S of each slice to join_mbus state before
+ * update the request state of all DBUS slices.
+ */
+static void update_mbus_pre_enable(struct intel_atomic_state *state)
+{
+	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
+	const int num_slices = INTEL_INFO(dev_priv)->num_supported_dbuf_slices;
+	u32 mbus_ctl, dbuf_min_tracker_val;
+	enum dbuf_slice slice;
+	const struct intel_dbuf_state *dbuf_state =
+		intel_atomic_get_new_dbuf_state(state);
+
+	if (!IS_ALDERLAKE_P(dev_priv))
+		return;
+
+	/*
+	 * TODO: Implement vblank synchronized MBUS joining changes.
+	 * Must be properly coordinated with dbuf reprogramming.
+	 */
+	if (dbuf_state->joined_mbus) {
+		mbus_ctl = MBUS_HASHING_MODE_1x4 | MBUS_JOIN |
+			MBUS_JOIN_PIPE_SELECT_NONE;
+		dbuf_min_tracker_val = DBUF_MIN_TRACKER_STATE_SERVICE(3);
+	} else {
+		mbus_ctl = MBUS_HASHING_MODE_2x2 |
+			MBUS_JOIN_PIPE_SELECT_NONE;
+		dbuf_min_tracker_val = DBUF_MIN_TRACKER_STATE_SERVICE(1);
+	}
+
+	intel_de_rmw(dev_priv, MBUS_CTL,
+		     MBUS_HASHING_MODE_MASK | MBUS_JOIN |
+		     MBUS_JOIN_PIPE_SELECT_MASK, mbus_ctl);
+
+	for (slice = DBUF_S1; slice < (num_slices + DBUF_S1); slice++)
+		intel_de_rmw(dev_priv, DBUF_CTL_S(slice),
+			     DBUF_MIN_TRACKER_STATE_SERVICE_MASK,
+			     dbuf_min_tracker_val);
+}
+
 void intel_dbuf_pre_plane_update(struct intel_atomic_state *state)
 {
 	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
@@ -7990,6 +8066,7 @@ void intel_dbuf_pre_plane_update(struct intel_atomic_state *state)
 
 	WARN_ON(!new_dbuf_state->base.changed);
 
+	update_mbus_pre_enable(state);
 	gen9_dbuf_slices_update(dev_priv,
 				old_dbuf_state->enabled_slices |
 				new_dbuf_state->enabled_slices);
diff --git a/drivers/gpu/drm/i915/intel_pm.h b/drivers/gpu/drm/i915/intel_pm.h
index 669c8d505677..bac72c859a84 100644
--- a/drivers/gpu/drm/i915/intel_pm.h
+++ b/drivers/gpu/drm/i915/intel_pm.h
@@ -78,9 +78,9 @@ struct intel_dbuf_state {
 	struct skl_ddb_entry ddb[I915_MAX_PIPES];
 	unsigned int weight[I915_MAX_PIPES];
 	u8 slices[I915_MAX_PIPES];
-
 	u8 enabled_slices;
 	u8 active_pipes;
+	bool joined_mbus;
 };
 
 int intel_dbuf_init(struct drm_i915_private *dev_priv);
