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

[Paulo Zanoni]

Hi

See comments inline.

2013/12/22 Nicolas Kalkhof <nkalkhof at web.de>:
> 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.

As far as I could check, your PCI ID is 0416, so your machine is not
ULT. As far as I know, your machine supports only up to PC7 state. I
may be wrong. Still, I will provide some comments below:


> During idle states (No X running) 915_pc8_status tells me that PC8 seems to be disabled:

To get into Pacakge C8 and deeper states you need all screens to be
disabled. You mentioned X is not running, so what exactly did you do
to disable all the screens?


> Requirements met: no

This means: either one or more screens are enabled, or the power well
is enabled, or both.


> GPU idle: no

Something is submitting work to the GPU.


> 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%.

Did you go to the "tunables" tab and switch everything to "good"? All
devices (not only graphics) need to be properly configured for the
machine to reach PC8+.



>           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%    |
>

Powertop doesn't show PC8, PC9 and PC10 states, which confirms my
belief that your machine does not support these states.


> 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

Why are you using all these options for i915? We recommend to stick to
the defaults since they are the best bug-free setup.

Thanks,
Paulo

>
> dmesg goes here: http://pastebin.ca/2516591
> Any ideas?
>
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-- 
Paulo Zanoni