+static void cpt_enable_fdi_bc_bifurcation(struct drm_device *dev)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ uint32_t temp;
+
+ temp = I915_READ(SOUTH_CHICKEN1);
+ if (temp & FDI_BC_BIFURCATION_SELECT)
+ return;
+
+ WARN_ON(I915_READ(FDI_RX_CTL(PIPE_B)) & FDI_RX_ENABLE);
+ WARN_ON(I915_READ(FDI_RX_CTL(PIPE_C)) & FDI_RX_ENABLE);
+
+ temp |= FDI_BC_BIFURCATION_SELECT;
+ DRM_DEBUG_KMS("enabling fdi C rx\n");
+ I915_WRITE(SOUTH_CHICKEN1, temp);
+ POSTING_READ(SOUTH_CHICKEN1);
+}
+
+static bool ironlake_check_fdi_lanes(struct intel_crtc *intel_crtc)
+{
+ struct drm_device *dev = intel_crtc->base.dev;
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ struct intel_crtc *pipe_B_crtc =
+ to_intel_crtc(dev_priv->pipe_to_crtc_mapping[PIPE_B]);
+
+ DRM_DEBUG_KMS("checking fdi config on pipe %i, lanes %i\n",
+ intel_crtc->pipe, intel_crtc->fdi_lanes);
+ if (intel_crtc->fdi_lanes > 4) {
+ DRM_DEBUG_KMS("invalid fdi lane config on pipe %i: %i lanes\n",
+ intel_crtc->pipe, intel_crtc->fdi_lanes);
+ /* Clamp lanes to avoid programming the hw with bogus values. */
+ intel_crtc->fdi_lanes = 4;
+
+ return false;
+ }
+
+ if (dev_priv->num_pipe == 2)
+ return true;
+
+ switch (intel_crtc->pipe) {
+ case PIPE_A:
+ return true;
+ case PIPE_B:
+ if (dev_priv->pipe_to_crtc_mapping[PIPE_C]->enabled &&
+ intel_crtc->fdi_lanes > 2) {
+ DRM_DEBUG_KMS("invalid shared fdi lane config on pipe %i: %i lanes\n",
+ intel_crtc->pipe, intel_crtc->fdi_lanes);
+ /* Clamp lanes to avoid programming the hw with bogus values. */
+ intel_crtc->fdi_lanes = 2;
+
+ return false;
+ }
+
+ if (intel_crtc->fdi_lanes > 2)
+ WARN_ON(I915_READ(SOUTH_CHICKEN1) & FDI_BC_BIFURCATION_SELECT);
+ else
+ cpt_enable_fdi_bc_bifurcation(dev);
+
+ return true;
+ case PIPE_C:
+ if (!pipe_B_crtc->base.enabled || pipe_B_crtc->fdi_lanes <= 2) {
+ if (intel_crtc->fdi_lanes > 2) {
+ DRM_DEBUG_KMS("invalid shared fdi lane config on pipe %i: %i lanes\n",
+ intel_crtc->pipe, intel_crtc->fdi_lanes);
+ /* Clamp lanes to avoid programming the hw with bogus values. */
+ intel_crtc->fdi_lanes = 2;
+
+ return false;
+ }
+ } else {
+ DRM_DEBUG_KMS("fdi link B uses too many lanes to enable link C\n");
+ return false;
+ }
+
+ cpt_enable_fdi_bc_bifurcation(dev);
+
+ return true;
+ default:
+ BUG();
+ }
+}
+