[v2 3/6] drm/i915/skl+: calculate plane pixel rate

[Shobhit Kumar <shobhit.kumar@intel.com>]

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

Don't use pipe pixel rate for plane pixel rate. Calculate plane pixel according
to formula

adjusted plane_pixel_rate = adjusted pipe_pixel_rate * downscale ammount

downscale amount = max[1, src_h/dst_h] * max[1, src_w/dst_w]
if 90/270 rotation use rotated width & height

v2: use intel_plane_state->visible instead of (fb == NULL) as per Matt's
    comment.

Cc: matthew.d.roper@intel.com
Signed-off-by: Kumar, Mahesh <mahesh1.kumar@intel.com>
---
 drivers/gpu/drm/i915/intel_drv.h |  2 +
 drivers/gpu/drm/i915/intel_pm.c  | 88 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 88 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index bc97012..bb2b1c7 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -638,6 +638,8 @@ struct intel_plane_wm_parameters {
 	u64 tiling;
 	unsigned int rotation;
 	uint16_t fifo_size;
+	/* Stores the adjusted plane pixel rate for WM calculation for SKL+ */
+	uint32_t plane_pixel_rate;
 };
 
 struct intel_plane {
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 708f329..40fff09 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2782,6 +2782,48 @@ skl_wm_plane_id(const struct intel_plane *plane)
 	}
 }
 
+/*
+ * This function takes drm_plane_state as input
+ * and decides the downscale amount according to the formula
+ *
+ * downscale amount = Max[1, Horizontal source size / Horizontal dest size]
+ *
+ * Return value is multiplied by 1000 to retain fractional part
+ * Caller should take care of dividing & Rounding off the value
+ */
+static uint32_t
+skl_plane_downscale_amount(const struct intel_plane *intel_plane)
+{
+	struct drm_plane_state *pstate = intel_plane->base.state;
+	struct intel_plane_state *intel_pstate = to_intel_plane_state(pstate);
+	uint32_t downscale_h, downscale_w;
+	uint32_t src_w, src_h, dst_w, dst_h, tmp;
+
+	/* If plane not visible return amount as unity */
+	if (!intel_pstate->visible)
+		return 1000;
+
+	src_w = drm_rect_width(&intel_pstate->src) >> 16;
+	src_h = drm_rect_height(&intel_pstate->src) >> 16;
+
+	dst_w = drm_rect_width(&intel_pstate->dst);
+	dst_h = drm_rect_height(&intel_pstate->dst);
+
+	if (intel_rotation_90_or_270(pstate->rotation))
+		swap(dst_w, dst_h);
+
+	/* Multiply by 1000 for precision */
+	tmp = (1000 * src_h) / dst_h;
+	downscale_h = max_t(uint32_t, 1000, tmp);
+
+	tmp = (1000 * src_w) / dst_w;
+	downscale_w = max_t(uint32_t, 1000, tmp);
+
+	/* Reducing precision to 3 decimal places */
+	return DIV_ROUND_UP(downscale_h * downscale_w, 1000);
+}
+
+
 static void
 skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
 				   const struct intel_crtc_state *cstate,
@@ -3183,10 +3225,10 @@ static bool skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 		swap(width, height);
 
 	bytes_per_pixel = drm_format_plane_cpp(fb->pixel_format, 0);
-	method1 = skl_wm_method1(skl_pipe_pixel_rate(cstate),
+	method1 = skl_wm_method1(intel_plane->wm.plane_pixel_rate,
 				 bytes_per_pixel,
 				 latency);
-	method2 = skl_wm_method2(skl_pipe_pixel_rate(cstate),
+	method2 = skl_wm_method2(intel_plane->wm.plane_pixel_rate,
 				 cstate->base.adjusted_mode.crtc_htotal,
 				 width,
 				 bytes_per_pixel,
@@ -3627,6 +3669,45 @@ static void skl_update_other_pipe_wm(struct drm_device *dev,
 	}
 }
 
+static uint32_t
+skl_plane_pixel_rate(struct intel_crtc_state *cstate, struct intel_plane *plane)
+{
+	uint32_t adjusted_pixel_rate;
+	uint32_t downscale_amount;
+
+	/*
+	 * adjusted plane pixel rate = adjusted pipe pixel rate
+	 * Plane pixel rate = adjusted plane pixel rate * plane down scale
+	 * amount
+	 */
+	adjusted_pixel_rate = skl_pipe_pixel_rate(cstate);
+	downscale_amount = skl_plane_downscale_amount(plane);
+
+	return DIV_ROUND_UP(adjusted_pixel_rate * downscale_amount,
+			1000);
+}
+
+static void skl_set_plane_pixel_rate(struct drm_crtc *crtc)
+{
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	struct intel_crtc_state *cstate = to_intel_crtc_state(crtc->state);
+	struct intel_plane *intel_plane = NULL;
+	struct drm_device *dev = crtc->dev;
+
+	if (!intel_crtc->active)
+		return;
+	for_each_intel_plane_on_crtc(dev, intel_crtc, intel_plane) {
+		struct drm_plane *plane = &intel_plane->base;
+
+		if (!to_intel_plane_state(plane->state)->visible)
+			continue;
+
+		intel_plane->wm.plane_pixel_rate = skl_plane_pixel_rate(cstate,
+				intel_plane);
+	}
+
+}
+
 static void skl_clear_wm(struct skl_wm_values *watermarks, enum pipe pipe)
 {
 	watermarks->wm_linetime[pipe] = 0;
@@ -3662,6 +3743,9 @@ static void skl_update_wm(struct drm_crtc *crtc)
 
 	skl_clear_wm(results, intel_crtc->pipe);
 
+	/* Calculate plane pixel rate for each plane in advance */
+	skl_set_plane_pixel_rate(crtc);
+
 	if (!skl_update_pipe_wm(crtc, &results->ddb, pipe_wm))
 		return;
 
-- 
2.5.0

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