drm/i915: Generalize skl_ddb_allocation_overlaps()

Make skl_ddb_allocation_overlaps() useful for other callers
besides skl_update_crtcs(). We'll need it to do plane updates
as well.

And while we're here we can reduce the stack utilization a
bit by noting that each struct skl_ddb_entry is 4 bytes whereas
a pointer to one is 8 bytes (on 64bit). So we'll switch to an
array of structs from the array of pointers we used before.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181101150605.18235-9-ville.syrjala@linux.intel.comReviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -12651,13 +12651,12 @@ static void skl_update_crtcs(struct drm_atomic_state *state)
 	int i;
 	u8 hw_enabled_slices = dev_priv->wm.skl_hw.ddb.enabled_slices;
 	u8 required_slices = intel_state->wm_results.ddb.enabled_slices;
-
-	const struct skl_ddb_entry *entries[I915_MAX_PIPES] = {};
+	struct skl_ddb_entry entries[I915_MAX_PIPES] = {};
 
 	for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i)
 		/* ignore allocations for crtc's that have been turned off. */
 		if (new_crtc_state->active)
-			entries[i] = &to_intel_crtc_state(old_crtc_state)->wm.skl.ddb;
+			entries[i] = to_intel_crtc_state(old_crtc_state)->wm.skl.ddb;
 
 	/* If 2nd DBuf slice required, enable it here */
 	if (INTEL_GEN(dev_priv) >= 11 && required_slices > hw_enabled_slices)
@@ -12683,14 +12682,13 @@ static void skl_update_crtcs(struct drm_atomic_state *state)
 			if (updated & cmask || !cstate->base.active)
 				continue;
 
-			if (skl_ddb_allocation_overlaps(dev_priv,
+			if (skl_ddb_allocation_overlaps(&cstate->wm.skl.ddb,
 							entries,
-							&cstate->wm.skl.ddb,
-							i))
+							INTEL_INFO(dev_priv)->num_pipes, i))
 				continue;
 
 			updated |= cmask;
-			entries[i] = &cstate->wm.skl.ddb;
+			entries[i] = cstate->wm.skl.ddb;
 
 			/*
 			 * If this is an already active pipe, it's DDB changed,

drivers/gpu/drm/i915/intel_drv.h

@@ -2191,10 +2191,9 @@ int intel_enable_sagv(struct drm_i915_private *dev_priv);
 int intel_disable_sagv(struct drm_i915_private *dev_priv);
 bool skl_wm_level_equals(const struct skl_wm_level *l1,
 			 const struct skl_wm_level *l2);
-bool skl_ddb_allocation_overlaps(struct drm_i915_private *dev_priv,
-				 const struct skl_ddb_entry **entries,
-				 const struct skl_ddb_entry *ddb,
-				 int ignore);
+bool skl_ddb_allocation_overlaps(const struct skl_ddb_entry *ddb,
+				 const struct skl_ddb_entry entries[],
+				 int num_entries, int ignore_idx);
 bool ilk_disable_lp_wm(struct drm_device *dev);
 int skl_check_pipe_max_pixel_rate(struct intel_crtc *intel_crtc,
 				  struct intel_crtc_state *cstate);

drivers/gpu/drm/i915/intel_pm.c

@@ -5186,16 +5186,15 @@ static inline bool skl_ddb_entries_overlap(const struct skl_ddb_entry *a,
 	return a->start < b->end && b->start < a->end;
 }
 
-bool skl_ddb_allocation_overlaps(struct drm_i915_private *dev_priv,
-				 const struct skl_ddb_entry **entries,
-				 const struct skl_ddb_entry *ddb,
-				 int ignore)
+bool skl_ddb_allocation_overlaps(const struct skl_ddb_entry *ddb,
+				 const struct skl_ddb_entry entries[],
+				 int num_entries, int ignore_idx)
 {
-	enum pipe pipe;
+	int i;
 
-	for_each_pipe(dev_priv, pipe) {
-		if (pipe != ignore && entries[pipe] &&
-		    skl_ddb_entries_overlap(ddb, entries[pipe]))
+	for (i = 0; i < num_entries; i++) {
+		if (i != ignore_idx &&
+		    skl_ddb_entries_overlap(ddb, &entries[i]))
 			return true;
 	}