This should fix breakage introduced in
commit 
ee7b9f93fd96a72e5d09e2b44024c11880873c6b
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Fri Apr 20 17:11:53 2012 +0100
    drm/i915: manage PCH PLLs separately from pipes
v2: Add a DRM_DEBUG_KMS message to explain why a given pll was
selected, suggested by Chris Wilson.
v3: Actually run git add.
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49712
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
 
                goto prepare;
        }
 
+       if (HAS_PCH_IBX(dev_priv->dev)) {
+               /* Ironlake PCH has a fixed PLL->PCH pipe mapping. */
+               i = intel_crtc->pipe;
+               pll = &dev_priv->pch_plls[i];
+
+               DRM_DEBUG_KMS("CRTC:%d using pre-allocated PCH PLL %x\n",
+                             intel_crtc->base.base.id, pll->pll_reg);
+
+               goto found;
+       }
+
        for (i = 0; i < dev_priv->num_pch_pll; i++) {
                pll = &dev_priv->pch_plls[i];