diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index eed9ead1b592..f26f61b0e7c8 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -170,8 +170,8 @@ static inline uint_fixed_16_16_t max_fixed_16_16(uint_fixed_16_16_t max1,
 	return max;
 }
 
-static inline uint_fixed_16_16_t fixed_16_16_div_round_up(uint32_t val,
-							  uint32_t d)
+static inline uint_fixed_16_16_t fixed_16_16_div(uint32_t val,
+						 uint32_t d)
 {
 	uint_fixed_16_16_t fp, res;
 
@@ -180,8 +180,8 @@ static inline uint_fixed_16_16_t fixed_16_16_div_round_up(uint32_t val,
 	return res;
 }
 
-static inline uint_fixed_16_16_t fixed_16_16_div_round_up_u64(uint32_t val,
-							      uint32_t d)
+static inline uint_fixed_16_16_t fixed_16_16_div_u64(uint32_t val,
+						     uint32_t d)
 {
 	uint_fixed_16_16_t res;
 	uint64_t interm_val;
@@ -206,6 +206,32 @@ static inline uint_fixed_16_16_t mul_u32_fixed_16_16(uint32_t val,
 	return fp;
 }
 
+static inline uint32_t mul_u32_fixed_16_16_round_up(uint32_t val,
+						    uint_fixed_16_16_t mul)
+{
+	uint64_t intermediate_val;
+	uint32_t result;
+
+	intermediate_val = (uint64_t) val * mul.val;
+	intermediate_val = DIV_ROUND_UP_ULL(intermediate_val, 1 << 16);
+	WARN_ON(intermediate_val >> 32);
+	result = clamp_t(uint32_t, intermediate_val, 0, ~0);
+	return result;
+}
+
+static inline uint_fixed_16_16_t mul_fixed_16_16(uint_fixed_16_16_t val,
+						 uint_fixed_16_16_t mul)
+{
+	uint64_t intermediate_val;
+	uint_fixed_16_16_t fp;
+
+	intermediate_val = (uint64_t) val.val * mul.val;
+	intermediate_val = intermediate_val >> 16;
+	WARN_ON(intermediate_val >> 32);
+	fp.val = clamp_t(uint32_t, intermediate_val, 0, ~0);
+	return fp;
+}
+
 static inline const char *yesno(bool v)
 {
 	return v ? "yes" : "no";
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 169c4908ad5b..09562d86c0fb 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3161,28 +3161,30 @@ void skl_ddb_get_hw_state(struct drm_i915_private *dev_priv,
  * Return value is provided in 16.16 fixed point form to retain fractional part.
  * Caller should take care of dividing & rounding off the value.
  */
-static uint32_t
+static uint_fixed_16_16_t
 skl_plane_downscale_amount(const struct intel_plane_state *pstate)
 {
-	uint32_t downscale_h, downscale_w;
 	uint32_t src_w, src_h, dst_w, dst_h;
+	uint_fixed_16_16_t fp_w_ratio, fp_h_ratio;
+	uint_fixed_16_16_t downscale_h, downscale_w;
 
 	if (WARN_ON(!pstate->base.visible))
-		return DRM_PLANE_HELPER_NO_SCALING;
+		return u32_to_fixed_16_16(0);
 
-	/* n.b., src is 16.16 fixed point, dst is whole integer */
-	src_w = drm_rect_width(&pstate->base.src);
-	src_h = drm_rect_height(&pstate->base.src);
+	src_w = drm_rect_width(&pstate->base.src) >> 16;
+	src_h = drm_rect_height(&pstate->base.src) >> 16;
 	dst_w = drm_rect_width(&pstate->base.dst);
 	dst_h = drm_rect_height(&pstate->base.dst);
 	if (drm_rotation_90_or_270(pstate->base.rotation))
 		swap(dst_w, dst_h);
 
-	downscale_h = max(src_h / dst_h, (uint32_t)DRM_PLANE_HELPER_NO_SCALING);
-	downscale_w = max(src_w / dst_w, (uint32_t)DRM_PLANE_HELPER_NO_SCALING);
+	fp_w_ratio = fixed_16_16_div(src_w, dst_w);
+	fp_h_ratio = fixed_16_16_div(src_h, dst_h);
+	downscale_w = max_fixed_16_16(fp_w_ratio, u32_to_fixed_16_16(1));
+	downscale_h = max_fixed_16_16(fp_h_ratio, u32_to_fixed_16_16(1));
 
 	/* Provide result in 16.16 fixed point */
-	return (uint64_t)downscale_w * downscale_h >> 16;
+	return mul_fixed_16_16(downscale_w, downscale_h);
 }
 
 static unsigned int
@@ -3191,10 +3193,11 @@ skl_plane_relative_data_rate(const struct intel_crtc_state *cstate,
 			     int y)
 {
 	struct intel_plane_state *intel_pstate = to_intel_plane_state(pstate);
-	uint32_t down_scale_amount, data_rate;
+	uint32_t data_rate;
 	uint32_t width = 0, height = 0;
 	struct drm_framebuffer *fb;
 	u32 format;
+	uint_fixed_16_16_t downscale_amount;
 
 	if (!intel_pstate->base.visible)
 		return 0;
@@ -3226,9 +3229,9 @@ skl_plane_relative_data_rate(const struct intel_crtc_state *cstate,
 		data_rate = width * height * fb->format->cpp[0];
 	}
 
-	down_scale_amount = skl_plane_downscale_amount(intel_pstate);
+	downscale_amount = skl_plane_downscale_amount(intel_pstate);
 
-	return (uint64_t)data_rate * down_scale_amount >> 16;
+	return mul_u32_fixed_16_16_round_up(data_rate, downscale_amount);
 }
 
 /*
@@ -3488,7 +3491,7 @@ static uint_fixed_16_16_t skl_wm_method1(uint32_t pixel_rate, uint8_t cpp,
 		return FP_16_16_MAX;
 
 	wm_intermediate_val = latency * pixel_rate * cpp;
-	ret = fixed_16_16_div_round_up_u64(wm_intermediate_val, 1000 * 512);
+	ret = fixed_16_16_div_u64(wm_intermediate_val, 1000 * 512);
 	return ret;
 }
 
@@ -3514,8 +3517,7 @@ static uint32_t skl_adjusted_plane_pixel_rate(const struct intel_crtc_state *cst
 					      struct intel_plane_state *pstate)
 {
 	uint64_t adjusted_pixel_rate;
-	uint64_t downscale_amount;
-	uint64_t pixel_rate;
+	uint_fixed_16_16_t downscale_amount;
 
 	/* Shouldn't reach here on disabled planes... */
 	if (WARN_ON(!pstate->base.visible))
@@ -3528,10 +3530,8 @@ static uint32_t skl_adjusted_plane_pixel_rate(const struct intel_crtc_state *cst
 	adjusted_pixel_rate = cstate->pixel_rate;
 	downscale_amount = skl_plane_downscale_amount(pstate);
 
-	pixel_rate = adjusted_pixel_rate * downscale_amount >> 16;
-	WARN_ON(pixel_rate != clamp_t(uint32_t, pixel_rate, 0, ~0));
-
-	return pixel_rate;
+	return mul_u32_fixed_16_16_round_up(adjusted_pixel_rate,
+					    downscale_amount);
 }
 
 static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
@@ -3617,8 +3617,8 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 	if (y_tiled) {
 		interm_pbpl = DIV_ROUND_UP(plane_bytes_per_line *
 					   y_min_scanlines, 512);
-		plane_blocks_per_line =
-		      fixed_16_16_div_round_up(interm_pbpl, y_min_scanlines);
+		plane_blocks_per_line = fixed_16_16_div(interm_pbpl,
+							y_min_scanlines);
 	} else if (x_tiled) {
 		interm_pbpl = DIV_ROUND_UP(plane_bytes_per_line, 512);
 		plane_blocks_per_line = u32_to_fixed_16_16(interm_pbpl);
