[PATCH 8/8] drm/i915/skl: WA for watermark calculation based on Arbitrated Display BW (v4)

[Matt Roper <matthew.d.roper@intel.com>]

From: "Kumar, Mahesh" <mahesh1.kumar@intel.com>

 If the arbitary display bandwidth is > 60% of memory bandwith, for
 x-tile we should increase latency at all levels by 15us.

 If the arbitary dsplay bandwidth is greater than 20% of memory bandwith
 in case of y-tile  being enabled, double the scan lines

v2: Update the commit message to explain the WA (shobhit)

v3: - Address Damien's comment, use DIV_ROUND_UP_ULL macro
    - Check both mem_speed and mem_channel to be valid before applying
      WA(shobhit)

v4 (by Matt):
 - Adjust calculations now that skl_plane_downscale_amount() returns
   a 16.16 fixed point value
 - Use pstate->visible instead of pstate->fb != NULL for determining
   whether a plane is active

Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Signed-off-by: Kumar, Mahesh <mahesh1.kumar@intel.com>
Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h |  9 ++++
 drivers/gpu/drm/i915/intel_pm.c | 97 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 106 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a2a7d8d..63b621a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1669,6 +1669,12 @@ enum intel_pipe_crc_source {
 	INTEL_PIPE_CRC_SOURCE_MAX,
 };
 
+enum watermark_memory_wa {
+	WATERMARK_WA_NONE,
+	WATERMARK_WA_X_TILED,
+	WATERMARK_WA_Y_TILED,
+};
+
 struct intel_pipe_crc_entry {
 	uint32_t frame;
 	uint32_t crc[5];
@@ -1973,6 +1979,9 @@ struct drm_i915_private {
 		/* Committed wm config */
 		struct intel_wm_config config;
 
+		/* This stores if WaterMark memory workaround is needed */
+		enum watermark_memory_wa mem_wa;
+
 		/*
 		 * The skl_wm_values structure is a bit too big for stack
 		 * allocation, so we keep the staging struct where we store
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 29d37d3..c1700af 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3286,6 +3286,11 @@ static bool skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 	if (latency == 0 || !cstate->base.active || !intel_pstate->visible)
 		return false;
 
+	if (dev_priv->wm.mem_wa != WATERMARK_WA_NONE) {
+		if (fb->modifier[0] == I915_FORMAT_MOD_X_TILED)
+			latency += 15;
+	}
+
 	width = drm_rect_width(&intel_pstate->src) >> 16;
 	height = drm_rect_height(&intel_pstate->src) >> 16;
 
@@ -3325,6 +3330,9 @@ static bool skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 				WARN(1, "Unsupported pixel depth for rotation");
 			}
 		}
+		if (dev_priv->wm.mem_wa == WATERMARK_WA_Y_TILED)
+			min_scanlines *= 2;
+
 		y_tile_minimum = plane_blocks_per_line * min_scanlines;
 		selected_result = max(method2, y_tile_minimum);
 	} else {
@@ -3776,6 +3784,94 @@ static void skl_set_plane_pixel_rate(struct drm_crtc *crtc)
 
 }
 
+static void
+skl_set_display_memory_wa(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = NULL;
+	struct intel_plane *intel_plane = NULL;
+	uint32_t num_active_crtc = 0;
+	uint64_t max_pixel_rate_pipe = 0;
+	uint64_t display_bw = 0, available_bw = 0;
+	bool y_tile_enabled = false;
+	int memory_portion = 0;
+
+	/* Verify that we got proper memory information */
+	if (!dev_priv->dmi.valid) {
+		dev_priv->wm.mem_wa = WATERMARK_WA_NONE;
+		return;
+	}
+
+	for_each_intel_crtc(dev, intel_crtc) {
+		uint64_t max_pixel_rate_plane = 0;
+		uint64_t pipe_bw;
+		uint32_t num_active_plane = 0;
+		const struct intel_crtc_state *cstate = NULL;
+
+		if (!intel_crtc->active)
+			continue;
+
+		cstate = to_intel_crtc_state(intel_crtc->base.state);
+		num_active_crtc++;
+
+		for_each_intel_plane_on_crtc(dev, intel_crtc, intel_plane) {
+			struct drm_plane *plane = &intel_plane->base;
+			struct drm_framebuffer *fb = plane->state->fb;
+			struct intel_plane_state *intel_pstate =
+				to_intel_plane_state(plane->state);
+			uint64_t plane_bw, interm_bw;
+
+			if (!intel_pstate->visible)
+				continue;
+			if (plane->type == DRM_PLANE_TYPE_CURSOR)
+				continue;
+
+			num_active_plane++;
+
+			if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED)
+				y_tile_enabled = true;
+
+			/*
+			 * planeBW = pixel_rate(MHz) * BPP * plane downscale
+			 *		amount * pipe downscale amount;
+			 *
+			 * skl_pipe_pixel_rate returns the adjusted value
+			 * according to the downscaling amount
+			 *
+			 * pixel rate is in KHz so divide it by 1000
+			 *
+			 * downscale factor is in 16.16 fixed point so shift
+			 * the result accordingly
+			 */
+			interm_bw = skl_pipe_pixel_rate(cstate)/1000 *
+				drm_format_plane_cpp(fb->pixel_format, 0) *
+				skl_plane_downscale_amount(intel_plane);
+
+			if (fb->pixel_format == DRM_FORMAT_NV12)
+				interm_bw += skl_pipe_pixel_rate(cstate)/1000 *
+					drm_format_plane_cpp(fb->pixel_format, 1) *
+					skl_plane_downscale_amount(intel_plane);
+
+			plane_bw = interm_bw >> 16;
+			max_pixel_rate_plane = max(max_pixel_rate_plane,
+						   plane_bw);
+		}
+		pipe_bw = max_pixel_rate_plane * num_active_plane;
+		max_pixel_rate_pipe = max(max_pixel_rate_pipe, pipe_bw);
+	}
+
+	display_bw = max_pixel_rate_pipe * num_active_crtc;
+	available_bw = dev_priv->dmi.mem_channel * dev_priv->dmi.mem_speed * 8;
+	memory_portion = DIV_ROUND_UP_ULL((display_bw * 100), available_bw);
+
+	if (y_tile_enabled && (memory_portion >= 20))
+		dev_priv->wm.mem_wa = WATERMARK_WA_Y_TILED;
+	else if (memory_portion >= 60)
+		dev_priv->wm.mem_wa = WATERMARK_WA_X_TILED;
+	else
+		dev_priv->wm.mem_wa = WATERMARK_WA_NONE;
+}
+
 static void skl_clear_wm(struct skl_wm_values *watermarks, enum pipe pipe)
 {
 	watermarks->wm_linetime[pipe] = 0;
@@ -3814,6 +3910,7 @@ static void skl_update_wm(struct drm_crtc *crtc)
 
 	/* Calculate plane pixel rate for each plane in advance */
 	skl_set_plane_pixel_rate(crtc);
+	skl_set_display_memory_wa(dev);
 
 	if (!skl_update_pipe_wm(crtc, &results->ddb, pipe_wm))
 		goto out;
-- 
2.1.4

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx