Created attachment 138406 [details]
dmesg

dmesg of the hang

Created attachment 138407 [details]
i915_error_state

i915_error_state

I see all fw is not latest:

https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/i915
DMC loaded: yes
DMC fw version: 1.7 <= Is newest
GuC loaded: yes
GuC fw version: 8.7 <= bxt_guc_ver9_29.bin latest
Not sure if this matters? 
HuC loaded: yes
HuC fw version: 1.7 <= bxt_huc_ver01_07_1398.bin I guess latest.

First of all. Sorry about spam.
This is mass update for our bugs. 

Sorry if you feel this annoying but with this trying to understand if bug still valid or not.
If bug investigation still in progress, please ignore this and I apologize!

If you think this is not anymore valid, please comment to the bug that can be closed.
If you haven't tested with our latest pre-upstream tree(drm-tip), can you do that also to see if issue is valid there still and if you cannot see issue there, please comment to the bug.

The GPU hang does look like a missed interrupt (though the debugging for that has much improved in more recent kernels), caused by old firmware.

Lin, any updates to this?

Closing, please re-open is issue still exists.

Thanks @Jani Saarinen
Yes please close this one as we have varified if update to 9.29 firmware this issue is gone.