FYI, we noticed the below changes on

git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
commit 05a2fb157e44a53c79133805d30eaada43911941 ("drm/i915: Consolidate forcewake code")

<3>[   19.736129] [drm:fw_domains_get [i915]] *ERROR* render: timed out waiting for forcewake ack request.
<3>[   19.740146] [drm:__gen6_gt_wait_for_thread_c0.isra.14 [i915]] *ERROR* GT thread status wait timed out
<6>[   19.740191] [drm] No MT forcewake available on Ivybridge, this can result in issues
<6>[   19.740206] [drm] when using vblank-synced partial screen updates.
<6>[   19.741933] [drm] Memory usable by graphics device = 2048M
<6>[   19.741950] [drm] Replacing VGA console driver

Thanks,
Ying Huang