I've bisected it to this commit
[root@fx6 linux2]# git bisect bad
df1e63942063a0638a5813e5904988d834db2665 is the first bad commit
commit df1e63942063a0638a5813e5904988d834db2665
Author: Rex Zhu
Date: Fri Sep 1 13:46:20 2017 +0800
drm/amd/powerplay: delete eventmgr layer in poweprlay
Thanks Tom.
The attached patch can fix this bug.
Best Regards
Rex
From: StDenis, Tom
Sent: Thursday, October 5, 2017 9:42 PM
To: amd-gfx mailing list
Cc: Zhu, Rex; Deucher, Alexander
Subject: tonga mclk regression
I've bisected it to this commit