From 91565c85b66db820f01894a971d39aaef60c4325 Mon Sep 17 00:00:00 2001
From: Matt Roper <matthew.d.roper@intel.com>
Date: Tue, 24 Jun 2014 17:05:02 -0700
Subject: [PATCH] drm/i915: Don't try to look up object for non-existent fb

crtc->primary->fb may be NULL upon entry to intel_pipe_set_base() if the
primary plane has previously been disabled via the universal plane
interface.  We need to check for NULL before trying to reference
old_fb's obj.

This fixes a regression introduced in

        commit a071fa00647bc9a3c53f917b236fff9aea175e3a
        Author: Daniel Vetter <daniel.vetter@ffwll.ch>
        Date:   Wed Jun 18 23:28:09 2014 +0200

        drm/i915: Introduce accurate frontbuffer tracking

Testcase: igt/kms_universal_plane
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
Reading git-format-patch failed