From 21b39d2a3adb798dc8dcbdb4abe23250ecfaf7e4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Wed, 18 Oct 2017 21:19:34 +0300
Subject: [PATCH] drm/i915: Unify error handling for missing DDI buf trans tables
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Git-commit: 21b39d2a3adb798dc8dcbdb4abe23250ecfaf7e4
Patch-mainline: v4.15-rc1
References: FATE#322643 bsc#1055900

Handle missing buf trans tables, or out of bounds buf trans levels
the same way everywhere. These should never be hit under normal
conditions, but let's play it safe for now.

V2: Avoid the hdmi_level=-1 case (James)

Cc: James Ausmus <james.ausmus@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171018181934.4229-1-ville.syrjala@linux.intel.com
Reviewed-by: James Ausmus <james.ausmus@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/intel_ddi.c |   27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -801,6 +801,11 @@ static int intel_ddi_hdmi_level(struct d
 	    hdmi_level >= n_hdmi_entries)
 		hdmi_level = hdmi_default_entry;
 
+	if (WARN_ON_ONCE(n_hdmi_entries == 0))
+		return 0;
+	if (WARN_ON_ONCE(hdmi_level >= n_hdmi_entries))
+		hdmi_level = n_hdmi_entries - 1;
+
 	return hdmi_level;
 }
 
@@ -864,6 +869,11 @@ static void intel_prepare_hdmi_ddi_buffe
 
 	ddi_translations_hdmi = intel_ddi_get_buf_trans_hdmi(dev_priv, &n_hdmi_entries);
 
+	if (WARN_ON_ONCE(!ddi_translations_hdmi))
+		return;
+	if (WARN_ON_ONCE(hdmi_level >= n_hdmi_entries))
+		hdmi_level = n_hdmi_entries - 1;
+
 	/* If we're boosting the current, set bit 31 of trans1 */
 	if (IS_GEN9_BC(dev_priv) &&
 	    dev_priv->vbt.ddi_port_info[port].hdmi_boost_level)
@@ -1847,6 +1857,11 @@ static void skl_ddi_set_iboost(struct in
 		else
 			ddi_translations = intel_ddi_get_buf_trans_dp(dev_priv, port, &n_entries);
 
+		if (WARN_ON_ONCE(!ddi_translations))
+			return;
+		if (WARN_ON_ONCE(level >= n_entries))
+			level = n_entries - 1;
+
 		iboost = ddi_translations[level].i_boost;
 	}
 
@@ -1877,6 +1892,11 @@ static void bxt_ddi_vswing_sequence(stru
 	else
 		ddi_translations = bxt_get_buf_trans_dp(dev_priv, &n_entries);
 
+	if (WARN_ON_ONCE(!ddi_translations))
+		return;
+	if (WARN_ON_ONCE(level >= n_entries))
+		level = n_entries - 1;
+
 	bxt_ddi_phy_set_signal_level(dev_priv, port,
 				     ddi_translations[level].margin,
 				     ddi_translations[level].scale,
@@ -1932,13 +1952,10 @@ static void cnl_ddi_vswing_program(struc
 	else
 		ddi_translations = cnl_get_buf_trans_dp(dev_priv, &n_entries);
 
-	if (WARN_ON(ddi_translations == NULL))
+	if (WARN_ON_ONCE(!ddi_translations))
 		return;
-
-	if (level >= n_entries) {
-		DRM_DEBUG_KMS("DDI translation not found for level %d. Using %d instead.", level, n_entries - 1);
+	if (WARN_ON_ONCE(level >= n_entries))
 		level = n_entries - 1;
-	}
 
 	/* Set PORT_TX_DW5 Scaling Mode Sel to 010b. */
 	val = I915_READ(CNL_PORT_TX_DW5_LN0(port));