Comment # 47 on bug 1011158 from Hubert Mantel

With firmware bxt_dmc_ver1_07.bin the problem still exists:

[    3.163081] [drm:finish_csr_load [i915]] *ERROR* Unknown stepping info,
firmware loading failed

However, I stumbled over this posting which indicates that this could be a
kernel problem:

https://askubuntu.com/questions/873109/unknown-stepping-info-firmware-loading-failed

"I don't know why, but my upgrade from 16.04 to 16.10 left me with an unchanged
kernel, the problematic 4.4 from Ubuntu 16.04. According to my recent reading,
the stepping info problem and freezing of Intel CPU's (that have embedded HD
graphics) is/was an issue through kernel 4.5, fixed in 4.6+. A fresh install of
16.10 gave me kernel 4.8, and it has been stable for days. My take-away lesson
is that to solve this problem, get kernel 4.6+. One way is to install a stable
16.10+ version fresh from bootable media (an incremental upgrade might not
suffice)"

I'm currently running the most recent kernel:

vdr:~ # uname -a
Linux vdr 4.4.72-18.12-default #1 SMP Mon Jun 19 14:11:41 UTC 2017 (9c03296)
x86_64 x86_64 x86_64 GNU/Linux
vdr:~ # 

But this still is one from the 4.4 series...