drm/i915: Use intel_pipe_wm in hsw_find_best_results

Let's try to keep using the intermediate intel_pipe_wm representation
for as long as possible. It avoids subtle knowledge about the
internals of the hardware registers when trying to choose the
best watermark configuration.

While at it replace the memset() w/ zero initialization.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -2722,8 +2722,6 @@ static void hsw_compute_wm_results(struct drm_device *dev,
 	struct intel_crtc *intel_crtc;
 	int level, wm_lp;
 
-	memset(results, 0, sizeof(*results));
-
 	results->enable_fbc_wm = merged->fbc_wm_enabled;
 
 	/* LP1+ register values */
@@ -2763,24 +2761,26 @@ static void hsw_compute_wm_results(struct drm_device *dev,
 
 /* Find the result with the highest level enabled. Check for enable_fbc_wm in
  * case both are at the same level. Prefer r1 in case they're the same. */
-static struct hsw_wm_values *hsw_find_best_result(struct hsw_wm_values *r1,
-						  struct hsw_wm_values *r2)
+static struct intel_pipe_wm *hsw_find_best_result(struct drm_device *dev,
+						  struct intel_pipe_wm *r1,
+						  struct intel_pipe_wm *r2)
 {
-	int i, val_r1 = 0, val_r2 = 0;
+	int level, max_level = ilk_wm_max_level(dev);
+	int level1 = 0, level2 = 0;
 
-	for (i = 0; i < 3; i++) {
-		if (r1->wm_lp[i] & WM3_LP_EN)
-			val_r1 = r1->wm_lp[i] & WM1_LP_LATENCY_MASK;
-		if (r2->wm_lp[i] & WM3_LP_EN)
-			val_r2 = r2->wm_lp[i] & WM1_LP_LATENCY_MASK;
+	for (level = 1; level <= max_level; level++) {
+		if (r1->wm[level].enable)
+			level1 = level;
+		if (r2->wm[level].enable)
+			level2 = level;
 	}
 
-	if (val_r1 == val_r2) {
-		if (r2->enable_fbc_wm && !r1->enable_fbc_wm)
+	if (level1 == level2) {
+		if (r2->fbc_wm_enabled && !r1->fbc_wm_enabled)
 			return r2;
 		else
 			return r1;
-	} else if (val_r1 > val_r2) {
+	} else if (level1 > level2) {
 		return r1;
 	} else {
 		return r2;
@@ -2891,10 +2891,10 @@ static void haswell_update_wm(struct drm_crtc *crtc)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct hsw_wm_maximums lp_max_1_2, lp_max_5_6;
 	struct hsw_pipe_wm_parameters params = {};
-	struct hsw_wm_values results_1_2, results_5_6, *best_results;
+	struct hsw_wm_values results = {};
 	enum intel_ddb_partitioning partitioning;
 	struct intel_pipe_wm pipe_wm = {};
-	struct intel_pipe_wm lp_wm_1_2 = {}, lp_wm_5_6 = {};
+	struct intel_pipe_wm lp_wm_1_2 = {}, lp_wm_5_6 = {}, *best_lp_wm;
 
 	hsw_compute_wm_parameters(crtc, &params, &lp_max_1_2, &lp_max_5_6);
 
@@ -2908,18 +2908,18 @@ static void haswell_update_wm(struct drm_crtc *crtc)
 	ilk_wm_merge(dev, &lp_max_1_2, &lp_wm_1_2);
 	ilk_wm_merge(dev, &lp_max_5_6, &lp_wm_5_6);
 
-	hsw_compute_wm_results(dev, &lp_wm_1_2, &results_1_2);
 	if (lp_max_1_2.pri != lp_max_5_6.pri) {
-		hsw_compute_wm_results(dev, &lp_wm_5_6, &results_5_6);
-		best_results = hsw_find_best_result(&results_1_2, &results_5_6);
+		best_lp_wm = hsw_find_best_result(dev, &lp_wm_1_2, &lp_wm_5_6);
 	} else {
-		best_results = &results_1_2;
+		best_lp_wm = &lp_wm_1_2;
 	}
 
-	partitioning = (best_results == &results_1_2) ?
+	hsw_compute_wm_results(dev, best_lp_wm, &results);
+
+	partitioning = (best_lp_wm == &lp_wm_1_2) ?
 		       INTEL_DDB_PART_1_2 : INTEL_DDB_PART_5_6;
 
-	hsw_write_wm_values(dev_priv, best_results, partitioning);
+	hsw_write_wm_values(dev_priv, &results, partitioning);
 }
 
 static void haswell_update_sprite_wm(struct drm_plane *plane,