};
 
 static const struct dbuf_slice_conf_entry adlp_allowed_dbufs[] = {
+       /*
+        * Keep the join_mbus cases first so check_mbus_joined()
+        * will prefer them over the !join_mbus cases.
+        */
        {
                .active_pipes = BIT(PIPE_A),
                .dbuf_mask = {
                },
                .join_mbus = true,
        },
+       {
+               .active_pipes = BIT(PIPE_A),
+               .dbuf_mask = {
+                       [PIPE_A] = BIT(DBUF_S1) | BIT(DBUF_S2),
+               },
+               .join_mbus = false,
+       },
+       {
+               .active_pipes = BIT(PIPE_B),
+               .dbuf_mask = {
+                       [PIPE_B] = BIT(DBUF_S3) | BIT(DBUF_S4),
+               },
+               .join_mbus = false,
+       },
        {
                .active_pipes = BIT(PIPE_A) | BIT(PIPE_B),
                .dbuf_mask = {
        return check_mbus_joined(active_pipes, adlp_allowed_dbufs);
 }
 
-static u8 compute_dbuf_slices(enum pipe pipe, u8 active_pipes,
+static u8 compute_dbuf_slices(enum pipe pipe, u8 active_pipes, bool join_mbus,
                              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)
+               if (dbuf_slices[i].active_pipes == active_pipes &&
+                   dbuf_slices[i].join_mbus == join_mbus)
                        return dbuf_slices[i].dbuf_mask[pipe];
        }
        return 0;
  * returns correspondent DBuf slice mask as stated in BSpec for particular
  * platform.
  */
-static u8 icl_compute_dbuf_slices(enum pipe pipe, u8 active_pipes)
+static u8 icl_compute_dbuf_slices(enum pipe pipe, u8 active_pipes, bool join_mbus)
 {
        /*
         * FIXME: For ICL this is still a bit unclear as prev BSpec revision
         * still here - we will need it once those additional constraints
         * pop up.
         */
-       return compute_dbuf_slices(pipe, active_pipes, icl_allowed_dbufs);
+       return compute_dbuf_slices(pipe, active_pipes, join_mbus,
+                                  icl_allowed_dbufs);
 }
 
-static u8 tgl_compute_dbuf_slices(enum pipe pipe, u8 active_pipes)
+static u8 tgl_compute_dbuf_slices(enum pipe pipe, u8 active_pipes, bool join_mbus)
 {
-       return compute_dbuf_slices(pipe, active_pipes, tgl_allowed_dbufs);
+       return compute_dbuf_slices(pipe, active_pipes, join_mbus,
+                                  tgl_allowed_dbufs);
 }
 
-static u32 adlp_compute_dbuf_slices(enum pipe pipe, u32 active_pipes)
+static u8 adlp_compute_dbuf_slices(enum pipe pipe, u8 active_pipes, bool join_mbus)
 {
-       return compute_dbuf_slices(pipe, active_pipes, adlp_allowed_dbufs);
+       return compute_dbuf_slices(pipe, active_pipes, join_mbus,
+                                  adlp_allowed_dbufs);
 }
 
-static u32 dg2_compute_dbuf_slices(enum pipe pipe, u32 active_pipes)
+static u8 dg2_compute_dbuf_slices(enum pipe pipe, u8 active_pipes, bool join_mbus)
 {
-       return compute_dbuf_slices(pipe, active_pipes, dg2_allowed_dbufs);
+       return compute_dbuf_slices(pipe, active_pipes, join_mbus,
+                                  dg2_allowed_dbufs);
 }
 
-static u8 skl_compute_dbuf_slices(struct intel_crtc *crtc, u8 active_pipes)
+static u8 skl_compute_dbuf_slices(struct intel_crtc *crtc, u8 active_pipes, bool join_mbus)
 {
        struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
        enum pipe pipe = crtc->pipe;
 
        if (IS_DG2(dev_priv))
-               return dg2_compute_dbuf_slices(pipe, active_pipes);
+               return dg2_compute_dbuf_slices(pipe, active_pipes, join_mbus);
        else if (IS_ALDERLAKE_P(dev_priv))
-               return adlp_compute_dbuf_slices(pipe, active_pipes);
+               return adlp_compute_dbuf_slices(pipe, active_pipes, join_mbus);
        else if (DISPLAY_VER(dev_priv) == 12)
-               return tgl_compute_dbuf_slices(pipe, active_pipes);
+               return tgl_compute_dbuf_slices(pipe, active_pipes, join_mbus);
        else if (DISPLAY_VER(dev_priv) == 11)
-               return icl_compute_dbuf_slices(pipe, active_pipes);
+               return icl_compute_dbuf_slices(pipe, active_pipes, join_mbus);
        /*
         * For anything else just return one slice yet.
         * Should be extended for other platforms.
                        return ret;
        }
 
+       if (IS_ALDERLAKE_P(dev_priv))
+               new_dbuf_state->joined_mbus =
+                       adlp_check_mbus_joined(new_dbuf_state->active_pipes);
+
        for_each_intel_crtc(&dev_priv->drm, crtc) {
                enum pipe pipe = crtc->pipe;
 
                new_dbuf_state->slices[pipe] =
-                       skl_compute_dbuf_slices(crtc, new_dbuf_state->active_pipes);
+                       skl_compute_dbuf_slices(crtc, new_dbuf_state->active_pipes,
+                                               new_dbuf_state->joined_mbus);
 
                if (old_dbuf_state->slices[pipe] == new_dbuf_state->slices[pipe])
                        continue;
 
        new_dbuf_state->enabled_slices = intel_dbuf_enabled_slices(new_dbuf_state);
 
-       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);
                }
 
                dbuf_state->slices[pipe] =
-                       skl_compute_dbuf_slices(crtc, dbuf_state->active_pipes);
+                       skl_compute_dbuf_slices(crtc, dbuf_state->active_pipes,
+                                               dbuf_state->joined_mbus);
 
                dbuf_state->weight[pipe] = intel_crtc_ddb_weight(crtc_state);