Hi,
On Thu, 2021-04-01 at 05:54 -0400, Rodrigo Vivi wrote:
On Thu, Apr 01, 2021 at 10:38:11AM +0100, Tvrtko Ursulin wrote:
...
I think it is possible to argue both ways.
HAS_RC6 means hardware has RC6 so if we view PMU as very low level we can say always export it.
If i915 had to turn it off (rc6->supported == false) due firmware or GVT-g, then we could say reporting zero RC6 is accurate in that sense. Only the reason "why it is zero" is missing for PMU users.
Or if we go with this patch we could say that presence of the PMU metric means RC6 is active and enabled, while absence means it is either not supported due platform (or firmware) or how the platform is getting used (GVT-g).
yeap, these 2 cases described well my mental conflict...
So I think patch is a bit better. I don't see it is adding more confusion.
As I said on the other patch I have no strong position on which is better, but if you and Eero feel that this works better for the current case, let's do it...
IMHO seeing case 1) i.e. zero RC6 could be slightly better from user point of view than not seeing RC6 at all, because:
A) user then knows that GPU is not entering RC6, and
B) then the question is why it's not going to RC6 => one can see from sysfs that it has been disabled
Whereas in case 2), the question is why there's no RC6 info, and user doesn't know whether GPU is suspended or not (i.e. why GPU power consumption is higher than expected). It would help if i-g-t could show e.g. "RC6 OFF" in that case.
- Eero