drm/i915/skl: New ddb allocation algorithm

This patch implements new DDB allocation algorithm as per HW team
recommendation. This algo takecare of scenario where we allocate less DDB
for the planes with lower relative pixel rate, but they require more DDB
to work.
It also takes care of enabling same watermark level for each
plane in crtc, for efficient power saving.

Changes since v1:
 - Rebase on top of Paulo's patch series

Changes since v2:
 - Fix the for loop condition to enable WM

Changes since v3:
 - Fix crash in cursor i-g-t reported by Maarten
 - Rebase after addressing Paulo's comments
 - Few other ULT fixes
Changes since v4:
 - Rebase on drm-tip
 - Added separate function to enable WM levels
Changes since v5:
 - Fix a crash identified in skl-6770HQ system
Changes since v6:
 - Address review comments from Matt
Changes since v7:
 - Fix failure return in skl_compute_plane_wm (Matt)
 - fix typo
Changes since v8:
 - Always check cursor wm enable irrespective of total_data_rate
Changes since v9:
 - fix typo

Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170601055918.4601-1-mahesh1.kumar@intel.com

drivers/gpu/drm/i915/intel_pm.c

@@ -4039,13 +4039,41 @@ skl_ddb_calc_min(const struct intel_crtc_state *cstate, int num_active,
 	minimum[PLANE_CURSOR] = skl_cursor_allocation(num_active);
 }
 
+static void
+skl_enable_plane_wm_levels(const struct drm_i915_private *dev_priv,
+			   uint16_t plane_ddb,
+			   uint16_t max_level,
+			   struct skl_plane_wm *wm)
+{
+	int level;
+	/*
+	 * Now enable all levels in WM structure which can be enabled
+	 * using current DDB allocation
+	 */
+	for (level = ilk_wm_max_level(dev_priv); level >= 0; level--) {
+		struct skl_wm_level *level_wm = &wm->wm[level];
+
+		if (level > max_level || level_wm->plane_res_b == 0
+				      || level_wm->plane_res_l >= 31
+				      || level_wm->plane_res_b >= plane_ddb) {
+			level_wm->plane_en = false;
+			level_wm->plane_res_b = 0;
+			level_wm->plane_res_l = 0;
+		} else {
+			level_wm->plane_en = true;
+		}
+	}
+}
+
 static int
 skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
+		      struct skl_pipe_wm *pipe_wm,
 		      struct skl_ddb_allocation *ddb /* out */)
 {
 	struct drm_atomic_state *state = cstate->base.state;
 	struct drm_crtc *crtc = cstate->base.crtc;
 	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	enum pipe pipe = intel_crtc->pipe;
 	struct skl_ddb_entry *alloc = &cstate->wm.skl.ddb;
@@ -4058,6 +4086,9 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
 	unsigned plane_data_rate[I915_MAX_PLANES] = {};
 	unsigned plane_y_data_rate[I915_MAX_PLANES] = {};
 	uint16_t total_min_blocks = 0;
+	uint16_t total_level_ddb;
+	uint16_t plane_blocks = 0;
+	int max_level, level;
 
 	/* Clear the partitioning for disabled planes. */
 	memset(ddb->plane[pipe], 0, sizeof(ddb->plane[pipe]));
@@ -4096,10 +4127,48 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
 		return -EINVAL;
 	}
 
-	alloc_size -= total_min_blocks;
-	ddb->plane[pipe][PLANE_CURSOR].start = alloc->end - minimum[PLANE_CURSOR];
+	alloc_size -= minimum[PLANE_CURSOR];
+	ddb->plane[pipe][PLANE_CURSOR].start = alloc->end -
+							minimum[PLANE_CURSOR];
 	ddb->plane[pipe][PLANE_CURSOR].end = alloc->end;
 
+	for (level = ilk_wm_max_level(dev_priv); level >= 0; level--) {
+		total_level_ddb = 0;
+		for_each_plane_id_on_crtc(intel_crtc, plane_id) {
+			/*
+			 * TODO: We should calculate watermark values for Y/UV
+			 * plane both in case of NV12 format and use both values
+			 * for ddb calculation. NV12 is disabled as of now, So
+			 * using only single/UV plane value here.
+			 */
+			struct skl_plane_wm *wm = &pipe_wm->planes[plane_id];
+			uint16_t plane_res_b = wm->wm[level].plane_res_b;
+			uint16_t min = minimum[plane_id] + y_minimum[plane_id];
+
+			if (plane_id == PLANE_CURSOR)
+				continue;
+
+			total_level_ddb += max(plane_res_b, min);
+		}
+
+		/*
+		 * If This level can successfully be enabled with the
+		 * pipe's current DDB allocation, then all lower levels are
+		 * guaranteed to succeed as well.
+		 */
+		if (total_level_ddb <= alloc_size)
+			break;
+	}
+
+	if ((level < 0) || (total_min_blocks > alloc_size)) {
+		DRM_DEBUG_KMS("Requested display configuration exceeds system DDB limitations");
+		DRM_DEBUG_KMS("minimum required %d/%d\n", (level < 0) ?
+				total_level_ddb : total_min_blocks, alloc_size);
+		return -EINVAL;
+	}
+	max_level = level;
+	alloc_size -= total_level_ddb;
+
 	/*
 	 * 2. Distribute the remaining space in proportion to the amount of
 	 * data each plane needs to fetch from memory.
@@ -4109,13 +4178,24 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
 	total_data_rate = skl_get_total_relative_data_rate(cstate,
 							   plane_data_rate,
 							   plane_y_data_rate);
+	/*
+	 * PLANE_CURSOR data rate is not included in total_data_rate.
+	 * If only cursor plane is enabled we have to enable its WM levels
+	 * explicitly before returning. Cursor has fixed ddb allocation,
+	 * So it's ok to always check cursor WM enabling before return.
+	 */
+	plane_blocks = skl_ddb_entry_size(&ddb->plane[pipe][PLANE_CURSOR]);
+	skl_enable_plane_wm_levels(dev_priv, plane_blocks, max_level,
+				   &pipe_wm->planes[PLANE_CURSOR]);
 	if (total_data_rate == 0)
 		return 0;
 
 	start = alloc->start;
 	for_each_plane_id_on_crtc(intel_crtc, plane_id) {
 		unsigned int data_rate, y_data_rate;
-		uint16_t plane_blocks, y_plane_blocks = 0;
+		uint16_t plane_blocks = 0, y_plane_blocks = 0;
+		struct skl_plane_wm *wm = &pipe_wm->planes[plane_id];
+		uint16_t plane_res_b = wm->wm[max_level].plane_res_b;
 
 		if (plane_id == PLANE_CURSOR)
 			continue;
@@ -4127,33 +4207,36 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
 		 * promote the expression to 64 bits to avoid overflowing, the
 		 * result is < available as data_rate / total_data_rate < 1
 		 */
-		plane_blocks = minimum[plane_id];
-		plane_blocks += div_u64((uint64_t)alloc_size * data_rate,
-					total_data_rate);
 
 		/* Leave disabled planes at (0,0) */
 		if (data_rate) {
+			plane_blocks = max(minimum[plane_id], plane_res_b);
+			plane_blocks += div_u64((uint64_t)alloc_size *
+					data_rate, total_data_rate);
 			ddb->plane[pipe][plane_id].start = start;
 			ddb->plane[pipe][plane_id].end = start + plane_blocks;
+			start += plane_blocks;
 		}
 
-		start += plane_blocks;
-
 		/*
 		 * allocation for y_plane part of planar format:
+		 * TODO: Once we start calculating watermark values for Y/UV
+		 * plane both consider it for initial allowed wm blocks.
 		 */
 		y_data_rate = plane_y_data_rate[plane_id];
 
-		y_plane_blocks = y_minimum[plane_id];
-		y_plane_blocks += div_u64((uint64_t)alloc_size * y_data_rate,
-					total_data_rate);
-
 		if (y_data_rate) {
+			y_plane_blocks = y_minimum[plane_id];
+			y_plane_blocks += div_u64((uint64_t)alloc_size *
+					y_data_rate, total_data_rate);
 			ddb->y_plane[pipe][plane_id].start = start;
 			ddb->y_plane[pipe][plane_id].end = start + y_plane_blocks;
+			start += y_plane_blocks;
 		}
-
-		start += y_plane_blocks;
+		skl_enable_plane_wm_levels(dev_priv,
+					   plane_blocks,
+					   max_level,
+					   wm);
 	}
 
 	return 0;
@@ -4243,11 +4326,9 @@ skl_adjusted_plane_pixel_rate(const struct intel_crtc_state *cstate,
 static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 				struct intel_crtc_state *cstate,
 				const struct intel_plane_state *intel_pstate,
-				uint16_t ddb_allocation,
 				int level,
 				uint16_t *out_blocks, /* out */
-				uint8_t *out_lines, /* out */
-				bool *enabled /* out */)
+				uint8_t *out_lines /* out */)
 {
 	struct intel_plane *plane = to_intel_plane(intel_pstate->base.plane);
 	const struct drm_plane_state *pstate = &intel_pstate->base;
@@ -4270,10 +4351,8 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 	bool y_tiled, x_tiled;
 
 	if (latency == 0 ||
-	    !intel_wm_plane_visible(cstate, intel_pstate)) {
-		*enabled = false;
+	    !intel_wm_plane_visible(cstate, intel_pstate))
 		return 0;
-	}
 
 	y_tiled = fb->modifier == I915_FORMAT_MOD_Y_TILED ||
 		  fb->modifier == I915_FORMAT_MOD_Yf_TILED;
@@ -4359,9 +4438,6 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 		if ((cpp * cstate->base.adjusted_mode.crtc_htotal / 512 < 1) &&
 		    (plane_bytes_per_line / 512 < 1))
 			selected_result = method2;
-		else if ((ddb_allocation && ddb_allocation /
-			fixed_16_16_to_u32_round_up(plane_blocks_per_line)) >= 1)
-			selected_result = min_fixed_16_16(method1, method2);
 		else if (latency >= linetime_us)
 			selected_result = min_fixed_16_16(method1, method2);
 		else
@@ -4381,64 +4457,42 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 		}
 	}
 
-	if (res_blocks >= ddb_allocation || res_lines > 31) {
-		*enabled = false;
-
-		/*
-		 * If there are no valid level 0 watermarks, then we can't
-		 * support this display configuration.
-		 */
-		if (level) {
-			return 0;
-		} else {
-			struct drm_plane *plane = pstate->plane;
+	if (res_lines >= 31 && level == 0) {
+		struct drm_plane *plane = pstate->plane;
 
-			DRM_DEBUG_KMS("Requested display configuration exceeds system watermark limitations\n");
-			DRM_DEBUG_KMS("[PLANE:%d:%s] blocks required = %u/%u, lines required = %u/31\n",
-				      plane->base.id, plane->name,
-				      res_blocks, ddb_allocation, res_lines);
-			return -EINVAL;
-		}
+		DRM_DEBUG_KMS("Requested display configuration exceeds system watermark limitations\n");
+		DRM_DEBUG_KMS("[PLANE:%d:%s] lines required = %u/31\n",
+				plane->base.id, plane->name, res_lines);
+		return -EINVAL;
 	}
 
 	*out_blocks = res_blocks;
 	*out_lines = res_lines;
-	*enabled = true;
 
 	return 0;
 }
 
 static int
 skl_compute_wm_levels(const struct drm_i915_private *dev_priv,
-		      struct skl_ddb_allocation *ddb,
 		      struct intel_crtc_state *cstate,
 		      const struct intel_plane_state *intel_pstate,
 		      struct skl_plane_wm *wm)
 {
-	struct intel_crtc *intel_crtc = to_intel_crtc(cstate->base.crtc);
-	struct drm_plane *plane = intel_pstate->base.plane;
-	struct intel_plane *intel_plane = to_intel_plane(plane);
-	uint16_t ddb_blocks;
-	enum pipe pipe = intel_crtc->pipe;
 	int level, max_level = ilk_wm_max_level(dev_priv);
 	int ret;
 
 	if (WARN_ON(!intel_pstate->base.fb))
 		return -EINVAL;
 
-	ddb_blocks = skl_ddb_entry_size(&ddb->plane[pipe][intel_plane->id]);
-
 	for (level = 0; level <= max_level; level++) {
 		struct skl_wm_level *result = &wm->wm[level];
 
 		ret = skl_compute_plane_wm(dev_priv,
 					   cstate,
 					   intel_pstate,
-					   ddb_blocks,
 					   level,
 					   &result->plane_res_b,
-					   &result->plane_res_l,
-					   &result->plane_en);
+					   &result->plane_res_l);
 		if (ret)
 			return ret;
 	}
@@ -4504,8 +4558,7 @@ static int skl_build_pipe_wm(struct intel_crtc_state *cstate,
 
 		wm = &pipe_wm->planes[plane_id];
 
-		ret = skl_compute_wm_levels(dev_priv, ddb, cstate,
-					    intel_pstate, wm);
+		ret = skl_compute_wm_levels(dev_priv, cstate, intel_pstate, wm);
 		if (ret)
 			return ret;
 		skl_compute_transition_wm(cstate, &wm->trans_wm);
@@ -4618,6 +4671,45 @@ bool skl_ddb_allocation_overlaps(const struct skl_ddb_entry **entries,
 	return false;
 }
 
+static int
+skl_ddb_add_affected_planes(struct intel_crtc_state *cstate,
+			    const struct skl_pipe_wm *old_pipe_wm,
+			    const struct skl_pipe_wm *pipe_wm)
+{
+	struct drm_atomic_state *state = cstate->base.state;
+	struct drm_device *dev = state->dev;
+	struct drm_crtc *crtc = cstate->base.crtc;
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct intel_atomic_state *intel_state = to_intel_atomic_state(state);
+	struct skl_ddb_allocation *new_ddb = &intel_state->wm_results.ddb;
+	struct skl_ddb_allocation *cur_ddb = &dev_priv->wm.skl_hw.ddb;
+	struct drm_plane_state *plane_state;
+	struct drm_plane *plane;
+	enum pipe pipe = intel_crtc->pipe;
+
+	WARN_ON(!drm_atomic_get_existing_crtc_state(state, crtc));
+
+	drm_for_each_plane_mask(plane, dev, cstate->base.plane_mask) {
+		enum plane_id plane_id = to_intel_plane(plane)->id;
+		const struct skl_plane_wm *wm = &pipe_wm->planes[plane_id];
+		const struct skl_plane_wm *old_wm = &old_pipe_wm->planes[plane_id];
+
+		if ((skl_ddb_entry_equal(&cur_ddb->plane[pipe][plane_id],
+					&new_ddb->plane[pipe][plane_id]) &&
+		    skl_ddb_entry_equal(&cur_ddb->y_plane[pipe][plane_id],
+					&new_ddb->y_plane[pipe][plane_id])) &&
+		    !memcmp(wm, old_wm, sizeof(struct skl_plane_wm)))
+			continue;
+
+		plane_state = drm_atomic_get_plane_state(state, plane);
+		if (IS_ERR(plane_state))
+			return PTR_ERR(plane_state);
+	}
+
+	return 0;
+}
+
 static int skl_update_pipe_wm(struct drm_crtc_state *cstate,
 			      const struct skl_pipe_wm *old_pipe_wm,
 			      struct skl_pipe_wm *pipe_wm, /* out */
@@ -4631,6 +4723,17 @@ static int skl_update_pipe_wm(struct drm_crtc_state *cstate,
 	if (ret)
 		return ret;
 
+	ret = skl_allocate_pipe_ddb(intel_cstate, pipe_wm, ddb);
+	if (ret)
+		return ret;
+	/*
+	 * TODO: Planes are included in state to arm WM registers.
+	 * Scope to optimize further, by just rewriting plane surf register.
+	 */
+	ret = skl_ddb_add_affected_planes(intel_cstate, old_pipe_wm, pipe_wm);
+	if (ret)
+		return ret;
+
 	if (!memcmp(old_pipe_wm, pipe_wm, sizeof(*pipe_wm)))
 		*changed = false;
 	else
@@ -4653,41 +4756,7 @@ pipes_modified(struct drm_atomic_state *state)
 }
 
 static int
-skl_ddb_add_affected_planes(struct intel_crtc_state *cstate)
-{
-	struct drm_atomic_state *state = cstate->base.state;
-	struct drm_device *dev = state->dev;
-	struct drm_crtc *crtc = cstate->base.crtc;
-	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
-	struct drm_i915_private *dev_priv = to_i915(dev);
-	struct intel_atomic_state *intel_state = to_intel_atomic_state(state);
-	struct skl_ddb_allocation *new_ddb = &intel_state->wm_results.ddb;
-	struct skl_ddb_allocation *cur_ddb = &dev_priv->wm.skl_hw.ddb;
-	struct drm_plane_state *plane_state;
-	struct drm_plane *plane;
-	enum pipe pipe = intel_crtc->pipe;
-
-	WARN_ON(!drm_atomic_get_existing_crtc_state(state, crtc));
-
-	drm_for_each_plane_mask(plane, dev, cstate->base.plane_mask) {
-		enum plane_id plane_id = to_intel_plane(plane)->id;
-
-		if (skl_ddb_entry_equal(&cur_ddb->plane[pipe][plane_id],
-					&new_ddb->plane[pipe][plane_id]) &&
-		    skl_ddb_entry_equal(&cur_ddb->y_plane[pipe][plane_id],
-					&new_ddb->y_plane[pipe][plane_id]))
-			continue;
-
-		plane_state = drm_atomic_get_plane_state(state, plane);
-		if (IS_ERR(plane_state))
-			return PTR_ERR(plane_state);
-	}
-
-	return 0;
-}
-
-static int
-skl_compute_ddb(struct drm_atomic_state *state)
+skl_include_affected_crtcs(struct drm_atomic_state *state)
 {
 	struct drm_device *dev = state->dev;
 	struct drm_i915_private *dev_priv = to_i915(dev);
@@ -4751,14 +4820,6 @@ skl_compute_ddb(struct drm_atomic_state *state)
 		cstate = intel_atomic_get_crtc_state(state, intel_crtc);
 		if (IS_ERR(cstate))
 			return PTR_ERR(cstate);
-
-		ret = skl_allocate_pipe_ddb(cstate, ddb);
-		if (ret)
-			return ret;
-
-		ret = skl_ddb_add_affected_planes(cstate);
-		if (ret)
-			return ret;
 	}
 
 	return 0;
@@ -4848,7 +4909,7 @@ skl_compute_wm(struct drm_atomic_state *state)
 	/* Clear all dirty flags */
 	results->dirty_pipes = 0;
 
-	ret = skl_compute_ddb(state);
+	ret = skl_include_affected_crtcs(state);
 	if (ret)
 		return ret;