[Intel-gfx] drm/i915: Enabling PC8 on Haswell

[Nicolas Kalkhof]

Sorry, last post got html infected!
 
Hello,
I've been trying to enable PC8 on my Haswell i7-4600M Notebook but i'm not sure if it is working properly.
During idle states (No X running) 915_pc8_status tells me that PC8 seems to be disabled:
Requirements met: no
GPU idle: no
Disable count: 3
IRQs disabled: no
Enabled: no
Is this supposed to be right?
 
Powertop 2.5 reports that Package C-States never go above pc3 while Core C7-HSW and GPU RC6 states are always reached with > 90%.
          Package   |             Core    |            CPU 0
                    |                     | C0 active   0.7%
                    |                     | POLL        0.0%    0.0 ms
                    |                     | C1E-HSW     0.9%    1.3 ms
C2 (pc2)   90.8%    |                     |
C3 (pc3)    0.0%    | C3 (cc3)    0.4%    | C3-HSW      0.4%    0.4 ms
C6 (pc6)    0.0%    | C6 (cc6)    0.0%    | C6-HSW      0.0%    0.0 ms
C7 (pc7)    0.0%    | C7 (cc7)   97.1%    | C7s-HSW    97.5%    5.8 ms
                    |             Core    |            CPU 1
                    |                     | C0 active   0.8%
                    |                     | POLL        0.0%    0.0 ms
                    |                     | C1E-HSW     0.0%    0.0 ms
                    |                     |
                    | C3 (cc3)    0.1%    | C3-HSW      0.1%    0.3 ms
                    | C6 (cc6)    0.0%    | C6-HSW      0.0%    0.0 ms
                    | C7 (cc7)   92.0%    | C7s-HSW    92.3%   12.0 ms
                    |             GPU     |
                    |                     |
                    | Powered On  0.6%    |
                    | RC6        99.4%    |
                    | RC6p        0.0%    |
 
Kernel is 3.13-rc4 from ~danvet/drm-intel/drm-intel-nightly
Params are: i915.i915_enable_rc6=1 pcie_aspm=force  i915.i915_disable_power_well=0 i915.enable_pc8=1 "acpi_osi=!Windows 2012" acpi_backlight=legacy
 
dmesg goes here: http://pastebin.ca/2516591
Any ideas?