diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 8ff8cc5..ab05695 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3827,26 +3827,27 @@ 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_crtc_state *cstate,
 			   const struct intel_plane_state *pstate)
 {
 	struct intel_plane *plane = to_intel_plane(pstate->base.plane);
-	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(!intel_wm_plane_visible(cstate, pstate)))
-		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 */
 	if (plane->id == PLANE_CURSOR) {
-		src_w = pstate->base.src_w;
-		src_h = pstate->base.src_h;
+		src_w = pstate->base.src_w >> 16;
+		src_h = pstate->base.src_h >> 16;
 		dst_w = pstate->base.crtc_w;
 		dst_h = pstate->base.crtc_h;
 	} else {
-		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);
 	}
@@ -3854,11 +3855,12 @@ skl_plane_downscale_amount(const struct intel_crtc_state *cstate,
 	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_fixed16(downscale_w, downscale_h);
 }
 
 static unsigned int
@@ -3868,10 +3870,11 @@ skl_plane_relative_data_rate(const struct intel_crtc_state *cstate,
 {
 	struct intel_plane *plane = to_intel_plane(pstate->plane);
 	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 down_scale_amount;
 
 	if (!intel_pstate->base.visible)
 		return 0;
@@ -3905,7 +3908,7 @@ skl_plane_relative_data_rate(const struct intel_crtc_state *cstate,
 
 	down_scale_amount = skl_plane_downscale_amount(cstate, intel_pstate);
 
-	return (uint64_t)data_rate * down_scale_amount >> 16;
+	return mul_round_up_u32_fixed16(data_rate, down_scale_amount);
 }
 
 /*
@@ -4191,8 +4194,7 @@ 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(!intel_wm_plane_visible(cstate, pstate)))
@@ -4205,10 +4207,8 @@ 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(cstate, 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_round_up_u32_fixed16(adjusted_pixel_rate,
+					    downscale_amount);
 }
 
 static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,