drm/i915: Check max number of lanes when registering DDI ports

DDI A and E share some of the lanes, so check that we have enough
lanes for the purpose we need before registering the encoders.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1449597590-6971-3-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 612400f..a69db46 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -3282,6 +3282,33 @@ void intel_ddi_init(struct drm_device *dev, enum port port)
        struct intel_encoder *intel_encoder;
        struct drm_encoder *encoder;
        bool init_hdmi, init_dp;
+       int max_lanes;
+
+       if (I915_READ(DDI_BUF_CTL(PORT_A)) & DDI_A_4_LANES) {
+               switch (port) {
+               case PORT_A:
+                       max_lanes = 4;
+                       break;
+               case PORT_E:
+                       max_lanes = 0;
+                       break;
+               default:
+                       max_lanes = 4;
+                       break;
+               }
+       } else {
+               switch (port) {
+               case PORT_A:
+                       max_lanes = 2;
+                       break;
+               case PORT_E:
+                       max_lanes = 2;
+                       break;
+               default:
+                       max_lanes = 4;
+                       break;
+               }
+       }
 
        init_hdmi = (dev_priv->vbt.ddi_port_info[port].supports_dvi ||
                     dev_priv->vbt.ddi_port_info[port].supports_hdmi);
@@ -3292,6 +3319,15 @@ void intel_ddi_init(struct drm_device *dev, enum port port)
                return;
        }
 
+       if (WARN(max_lanes == 0,
+                "No lanes for port %c\n", port_name(port)))
+               return;
+
+       if (WARN(init_hdmi && max_lanes < 4,
+                "Not enough lanes (%d) for HDMI on port %c\n",
+                max_lanes, port_name(port)))
+               init_hdmi = false;
+
        intel_dig_port = kzalloc(sizeof(*intel_dig_port), GFP_KERNEL);
        if (!intel_dig_port)
                return;