Created attachment 160341 [details]
dmesg output from 3 resume cycles

Using a Radeon R9 270X and kernel 3.18.0 I get the following error message only after resume from S3 state:

[drm:si_dpm_set_power_state] *ERROR* si_set_sw_state failed

I would like to notice that this also happened with older kernel versions (3.17 and 3.16 with radeon.dpm=1) and other cards. My other PC has a HD 5450 with the same problem (slightly other ERROR string as its not SI).
Besides the error message, I cannot see any strange behaviour, performance is good, no freezes etc. . But it sounds like performance level switching is not working correctly?

I added the dmesg output showing three resume cycles with the mentioned error message as attachment.

Thanks