drm/i915: Hoover the level>=n_entries WARN into intel_ddi_level()

All callers of intel_ddi_level() duplicate the check+WARN
to make sure the returned level is actually present in the
appropriate buf_trans table. Let's push that stuff into
intel_ddi_level() so the callers don't have to worry about it.
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211001130107.1746-7-ville.syrjala@linux.intel.com

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

@@ -151,8 +151,6 @@ static void hsw_prepare_hdmi_ddi_buffers(struct intel_encoder *encoder,
 	trans = encoder->get_buf_trans(encoder, crtc_state, &n_entries);
 	if (drm_WARN_ON_ONCE(&dev_priv->drm, !trans))
 		return;
-	if (drm_WARN_ON_ONCE(&dev_priv->drm, level >= n_entries))
-		level = n_entries - 1;
 
 	/* If we're boosting the current, set bit 31 of trans1 */
 	if (has_iboost(dev_priv) &&
@@ -987,8 +985,6 @@ static void skl_ddi_set_iboost(struct intel_encoder *encoder,
 		trans = encoder->get_buf_trans(encoder, crtc_state, &n_entries);
 		if (drm_WARN_ON_ONCE(&dev_priv->drm, !trans))
 			return;
-		if (drm_WARN_ON_ONCE(&dev_priv->drm, level >= n_entries))
-			level = n_entries - 1;
 
 		iboost = trans->entries[level].hsw.i_boost;
 	}
@@ -1047,8 +1043,6 @@ static void icl_ddi_combo_vswing_program(struct intel_encoder *encoder,
 	trans = encoder->get_buf_trans(encoder, crtc_state, &n_entries);
 	if (drm_WARN_ON_ONCE(&dev_priv->drm, !trans))
 		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);
@@ -1173,8 +1167,6 @@ static void icl_mg_phy_set_signal_levels(struct intel_encoder *encoder,
 	trans = encoder->get_buf_trans(encoder, crtc_state, &n_entries);
 	if (drm_WARN_ON_ONCE(&dev_priv->drm, !trans))
 		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++) {
@@ -1296,8 +1288,6 @@ static void tgl_dkl_phy_set_signal_levels(struct intel_encoder *encoder,
 	trans = encoder->get_buf_trans(encoder, crtc_state, &n_entries);
 	if (drm_WARN_ON_ONCE(&dev_priv->drm, !trans))
 		return;
-	if (drm_WARN_ON_ONCE(&dev_priv->drm, level >= n_entries))
-		level = n_entries - 1;
 
 	dpcnt_mask = (DKL_TX_PRESHOOT_COEFF_MASK |
 		      DKL_TX_DE_EMPAHSIS_COEFF_MASK |
@@ -1367,10 +1357,23 @@ static int intel_ddi_dp_level(struct intel_dp *intel_dp)
 int intel_ddi_level(struct intel_encoder *encoder,
 		    const struct intel_crtc_state *crtc_state)
 {
+	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
+	const struct intel_ddi_buf_trans *trans;
+	int level, n_entries;
+
+	trans = encoder->get_buf_trans(encoder, crtc_state, &n_entries);
+	if (drm_WARN_ON_ONCE(&i915->drm, !trans))
+		return 0;
+
 	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI))
-		return intel_ddi_hdmi_level(encoder, crtc_state);
+		level = intel_ddi_hdmi_level(encoder, crtc_state);
 	else
-		return intel_ddi_dp_level(enc_to_intel_dp(encoder));
+		level = intel_ddi_dp_level(enc_to_intel_dp(encoder));
+
+	if (drm_WARN_ON_ONCE(&i915->drm, level >= n_entries))
+		level = n_entries - 1;
+
+	return level;
 }
 
 static void

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

@@ -282,8 +282,6 @@ void bxt_ddi_phy_set_signal_levels(struct intel_encoder *encoder,
 	trans = encoder->get_buf_trans(encoder, crtc_state, &n_entries);
 	if (drm_WARN_ON_ONCE(&dev_priv->drm, !trans))
 		return;
-	if (drm_WARN_ON_ONCE(&dev_priv->drm, level >= n_entries))
-		level = n_entries - 1;
 
 	bxt_port_to_phy_channel(dev_priv, encoder->port, &phy, &ch);
 

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

@@ -64,8 +64,6 @@ void intel_snps_phy_set_signal_levels(struct intel_encoder *encoder,
 	trans = encoder->get_buf_trans(encoder, crtc_state, &n_entries);
 	if (drm_WARN_ON_ONCE(&dev_priv->drm, !trans))
 		return;
-	if (drm_WARN_ON_ONCE(&dev_priv->drm, level < 0 || level >= n_entries))
-		level = n_entries - 1;
 
 	for (ln = 0; ln < 4; ln++) {
 		u32 val = 0;