drm/i915: Reuse intel_adjusted_rate() for pfit pixel rate adjustment

Replace the hand rolled pfit downscale calculations with
intel_adjusted_rate().
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210330184254.6290-2-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_atomic_plane.c

@@ -133,7 +133,7 @@ intel_plane_destroy_state(struct drm_plane *plane,
 	kfree(plane_state);
 }
 
-static unsigned int intel_adjusted_rate(const struct drm_rect *src,
+unsigned int intel_adjusted_rate(const struct drm_rect *src,
 				 const struct drm_rect *dst,
 				 unsigned int rate)
 {

drivers/gpu/drm/i915/display/intel_atomic_plane.h

@@ -10,6 +10,7 @@
 
 struct drm_plane;
 struct drm_property;
+struct drm_rect;
 struct intel_atomic_state;
 struct intel_crtc;
 struct intel_crtc_state;
@@ -18,6 +19,9 @@ struct intel_plane_state;
 
 extern const struct drm_plane_helper_funcs intel_plane_helper_funcs;
 
+unsigned int intel_adjusted_rate(const struct drm_rect *src,
+				 const struct drm_rect *dst,
+				 unsigned int rate);
 unsigned int intel_plane_pixel_rate(const struct intel_crtc_state *crtc_state,
 				    const struct intel_plane_state *plane_state);
 

drivers/gpu/drm/i915/display/intel_display.c

@@ -3984,7 +3984,7 @@ static bool intel_crtc_supports_double_wide(const struct intel_crtc *crtc)
 static u32 ilk_pipe_pixel_rate(const struct intel_crtc_state *crtc_state)
 {
 	u32 pixel_rate = crtc_state->hw.pipe_mode.crtc_clock;
-	unsigned int pipe_w, pipe_h, pfit_w, pfit_h;
+	struct drm_rect src;
 
 	/*
 	 * We only use IF-ID interlacing. If we ever use
@@ -3994,23 +3994,12 @@ static u32 ilk_pipe_pixel_rate(const struct intel_crtc_state *crtc_state)
 	if (!crtc_state->pch_pfit.enabled)
 		return pixel_rate;
 
-	pipe_w = crtc_state->pipe_src_w;
-	pipe_h = crtc_state->pipe_src_h;
+	drm_rect_init(&src, 0, 0,
+		      crtc_state->pipe_src_w << 16,
+		      crtc_state->pipe_src_h << 16);
 
-	pfit_w = drm_rect_width(&crtc_state->pch_pfit.dst);
-	pfit_h = drm_rect_height(&crtc_state->pch_pfit.dst);
-
-	if (pipe_w < pfit_w)
-		pipe_w = pfit_w;
-	if (pipe_h < pfit_h)
-		pipe_h = pfit_h;
-
-	if (drm_WARN_ON(crtc_state->uapi.crtc->dev,
-			!pfit_w || !pfit_h))
-		return pixel_rate;
-
-	return div_u64(mul_u32_u32(pixel_rate, pipe_w * pipe_h),
-		       pfit_w * pfit_h);
+	return intel_adjusted_rate(&src, &crtc_state->pch_pfit.dst,
+				   pixel_rate);
 }
 
 static void intel_mode_from_crtc_timings(struct drm_display_mode *mode,