drm/i915/skl+: Scaling not supported in IF-ID Interlace mode

GEN9+ Interlace fetch mode doesn't support pipe/plane scaling,
This patch adds check to fail the flip if pipe/plane scaling is
requested in Interlace fetch mode.

Changes since V1:
 - move check to skl_update_scaler (ville)
 - mode to adjusted_mode (ville)
 - combine pipe/plane scaling check
Changes since V2:
 - Indentation fix
 - Added TODO to handle/reject NV12 with interlace mode

Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170630121100.20159-3-mahesh1.kumar@intel.com
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -4612,6 +4612,9 @@ skl_update_scaler(struct intel_crtc_state *crtc_state, bool force_detach,
 		&crtc_state->scaler_state;
 	struct intel_crtc *intel_crtc =
 		to_intel_crtc(crtc_state->base.crtc);
+	struct drm_i915_private *dev_priv = to_i915(intel_crtc->base.dev);
+	const struct drm_display_mode *adjusted_mode =
+		&crtc_state->base.adjusted_mode;
 	int need_scaling;
 
 	/*
@@ -4621,6 +4624,18 @@ skl_update_scaler(struct intel_crtc_state *crtc_state, bool force_detach,
 	 */
 	need_scaling = src_w != dst_w || src_h != dst_h;
 
+	/*
+	 * Scaling/fitting not supported in IF-ID mode in GEN9+
+	 * TODO: Interlace fetch mode doesn't support YUV420 planar formats.
+	 * Once NV12 is enabled, handle it here while allocating scaler
+	 * for NV12.
+	 */
+	if (INTEL_GEN(dev_priv) >= 9 && crtc_state->base.enable &&
+	    need_scaling && adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE) {
+		DRM_DEBUG_KMS("Pipe/Plane scaling not supported with IF-ID mode\n");
+		return -EINVAL;
+	}
+
 	/*
 	 * if plane is being disabled or scaler is no more required or force detach
 	 *  - free scaler binded to this plane/crtc