Power limit OD stopped working for navi10 - broken on previously working commit

[Matt Coffin]

I was doing some benchmarking, and noticed some poor performance,
indicating that my overdrive settings were not in place, which they
were. hwmon/power1_cap reports the correctly adjusted value after it is
written to, and I confirmed with a quick patch that the updated power
limit value is actually being returned from the SMU after it is set, yet
the card refuses to go over stock settings (+/- 3% of stock power draw,
even with a 50% increase in power limit).

Since I worked on that code a while back, I went to go bisect, using
c39f062e881dcc6ab4c1c1c5835dc774be1bcfd6 as a starting location, since I
know that commit had working power limit overdrive before.

Strangely, I'm seeing the same behavior on that
previously-known-to-be-working commit!

This happens for both *increased* and *decreased* power limits. sysfs
reflects the change, but I see no change in the actual power draw on the
card, and for the *increased* case, performance reflects a card that is
throttling due to power limits.

Were there any firmware changes or anything that could be causing this
since I don't know where to start since a previously-working commit is
now somehow broken.

Since the behavior seems to have changed on me, it would also be
incredibly helpful if anyone can either confirm or deny that they can
reproduce this problem (or not) off of the latest codebase OR
c39f062e881dcc6ab4c1c1c5835dc774be1bcfd6.

Any help, testing information, or simple confirm/deny from your side
would go a long way.

Thanks in advance,
Matt