drm/i915: Unify error handling for missing DDI buf trans tables

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>

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 5ee0e33e2c00df9437f3ad626be3ea69c46aabdb..cd7a0d979a105f62ba4bd72c63e3cba5e383f484 100644 (file)
--- 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 drm_i915_private *dev_priv, enum port por
            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_buffers(struct intel_encoder *encoder,
 
        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 intel_encoder *encoder,
                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(struct intel_encoder *encoder,
        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(struct intel_encoder *encoder,
        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));