drm/i915: Unify the sanity checks for the buf trans tables

Get rid of the "I like my random new style best" approach and unify
the handling for the DDI buf trans table sanity checks once again.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201207203512.1718-2-ville.syrjala@linux.intel.comReviewed-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NJosé Roberto de Souza <jose.souza@intel.com>

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

@@ -2702,15 +2702,11 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder,
 		ddi_translations = ehl_get_combo_buf_trans(encoder, crtc_state, &n_entries);
 	else
 		ddi_translations = icl_get_combo_buf_trans(encoder, crtc_state, &n_entries);
-	if (!ddi_translations)
-		return;
 
-	if (level >= n_entries) {
-		drm_dbg_kms(&dev_priv->drm,
-			    "DDI translation not found for level %d. Using %d instead.",
-			    level, n_entries - 1);
+	if (drm_WARN_ON_ONCE(&dev_priv->drm, !ddi_translations))
+		return;
+	if (drm_WARN_ON_ONCE(&dev_priv->drm, level >= n_entries))
 		level = n_entries - 1;
-	}
 
 	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_EDP)) {
 		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
@@ -2831,12 +2827,11 @@ static void icl_mg_phy_ddi_vswing_sequence(struct intel_encoder *encoder,
 	u32 val;
 
 	ddi_translations = icl_get_mg_buf_trans(encoder, crtc_state, &n_entries);
-	if (level >= n_entries) {
-		drm_dbg_kms(&dev_priv->drm,
-			    "DDI translation not found for level %d. Using %d instead.",
-			    level, n_entries - 1);
+
+	if (drm_WARN_ON_ONCE(&dev_priv->drm, !ddi_translations))
+		return;
+	if (drm_WARN_ON_ONCE(&dev_priv->drm, level >= n_entries))
 		level = n_entries - 1;
-	}
 
 	/* Set MG_TX_LINK_PARAMS cri_use_fs32 to 0. */
 	for (ln = 0; ln < 2; ln++) {
@@ -2968,7 +2963,9 @@ tgl_dkl_phy_ddi_vswing_sequence(struct intel_encoder *encoder,
 
 	ddi_translations = tgl_get_dkl_buf_trans(encoder, crtc_state, &n_entries);
 
-	if (level >= n_entries)
+	if (drm_WARN_ON_ONCE(&dev_priv->drm, !ddi_translations))
+		return;
+	if (drm_WARN_ON_ONCE(&dev_priv->drm, level >= n_entries))
 		level = n_entries - 1;
 
 	dpcnt_mask = (DKL_TX_PRESHOOT_COEFF_MASK |