>  starting with BTC, there is one state that is used for both
> + * MH and SH. Difference is that we always use the high clock index for
> + * mclk.

I don't think that is correct. It can clearly be seen in Windows that Barts
uses different idles for multi head than it does for single head, but uses the
same mid and high. Cayman has a different system to barts too I suspect.

> ((rdev->pm.profile_index == PM_PROFILE_MID_MH_IDX) ||
> + (rdev->pm.profile_index == PM_PROFILE_LOW_MH_IDX)))
> + mclk = rdev->pm.power_state[rdev->pm.requested_power_state_index].
> + clock_info[rdev->pm.profiles[PM_PROFILE_HIGH_MH_IDX].dpms_on_cm_idx].mclk;

Isn't that dangerous? It makes the card operate outside of the bios table
profiles. You would, in some cases, be increasing the memory clock without
increasing the voltage.