drm/i915: Simplify skl_max_scale()

Now that the planes declare their minimum cdclk requirements properly
we don't need to check the cdclk in skl_max_scale() anymore. Just check
against the maximum downscale ratio, and move the code next to it's
only caller.

v2: Add a comment explaining the HQ vs. not thing
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191015193035.25982-7-ville.syrjala@linux.intel.com

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

@@ -15145,44 +15145,6 @@ intel_cleanup_plane_fb(struct drm_plane *plane,
 	intel_plane_unpin_fb(old_plane_state);
 }
 
-int
-skl_max_scale(const struct intel_crtc_state *crtc_state,
-	      const struct drm_format_info *format)
-{
-	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
-	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
-	int max_scale;
-	int crtc_clock, max_dotclk, tmpclk1, tmpclk2;
-
-	if (!crtc_state->base.enable)
-		return DRM_PLANE_HELPER_NO_SCALING;
-
-	crtc_clock = crtc_state->base.adjusted_mode.crtc_clock;
-	max_dotclk = to_intel_atomic_state(crtc_state->base.state)->cdclk.logical.cdclk;
-
-	if (IS_GEMINILAKE(dev_priv) || INTEL_GEN(dev_priv) >= 10)
-		max_dotclk *= 2;
-
-	if (WARN_ON_ONCE(!crtc_clock || max_dotclk < crtc_clock))
-		return DRM_PLANE_HELPER_NO_SCALING;
-
-	/*
-	 * skl max scale is lower of:
-	 *    close to 3 but not 3, -1 is for that purpose
-	 *            or
-	 *    cdclk/crtc_clock
-	 */
-	if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv) ||
-	    !drm_format_info_is_yuv_semiplanar(format))
-		tmpclk1 = 0x30000 - 1;
-	else
-		tmpclk1 = 0x20000 - 1;
-	tmpclk2 = (1 << 8) * ((max_dotclk << 8) / crtc_clock);
-	max_scale = min(tmpclk1, tmpclk2);
-
-	return max_scale;
-}
-
 /**
  * intel_plane_destroy - destroy a plane
  * @plane: plane to destroy

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

@@ -563,8 +563,6 @@ void intel_crtc_arm_fifo_underrun(struct intel_crtc *crtc,
 
 u16 skl_scaler_calc_phase(int sub, int scale, bool chroma_center);
 int skl_update_scaler_crtc(struct intel_crtc_state *crtc_state);
-int skl_max_scale(const struct intel_crtc_state *crtc_state,
-		  const struct drm_format_info *format);
 u32 glk_plane_color_ctl(const struct intel_crtc_state *crtc_state,
 			const struct intel_plane_state *plane_state);
 u32 glk_plane_color_ctl_crtc(const struct intel_crtc_state *crtc_state);

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

@@ -2120,6 +2120,22 @@ static int skl_plane_check_nv12_rotation(const struct intel_plane_state *plane_s
 	return 0;
 }
 
+static int skl_plane_max_scale(struct drm_i915_private *dev_priv,
+			       const struct drm_framebuffer *fb)
+{
+	/*
+	 * We don't yet know the final source width nor
+	 * whether we can use the HQ scaler mode. Assume
+	 * the best case.
+	 * FIXME need to properly check this later.
+	 */
+	if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv) ||
+	    !drm_format_info_is_yuv_semiplanar(fb->format))
+		return 0x30000 - 1;
+	else
+		return 0x20000 - 1;
+}
+
 static int skl_plane_check(struct intel_crtc_state *crtc_state,
 			   struct intel_plane_state *plane_state)
 {
@@ -2137,7 +2153,7 @@ static int skl_plane_check(struct intel_crtc_state *crtc_state,
 	/* use scaler when colorkey is not required */
 	if (!plane_state->ckey.flags && intel_fb_scalable(fb)) {
 		min_scale = 1;
-		max_scale = skl_max_scale(crtc_state, fb->format);
+		max_scale = skl_plane_max_scale(dev_priv, fb);
 	}
 
 	ret = drm_atomic_helper_check_plane_state(&plane_state->base,