[Nouveau] pstates

[James]

> Performance level selection (also known as "reclocking") is not supported yet.

It's not supported but does it work in some cases.

[    0.000000] Command line: root=/dev/sdc1 rootfstype=ext4 raid=noautodetect ro nouveau.pstate=1
[    0.000000] Kernel command line: root=/dev/sdc1 rootfstype=ext4 raid=noautodetect ro nouveau.pstate=1
[    2.108531] nouveau  [  DEVICE][0000:01:00.0] BOOT0  : 0x0e7060a2
[    2.108536] nouveau  [  DEVICE][0000:01:00.0] Chipset: GK107 (NVE7)
[    2.108539] nouveau  [  DEVICE][0000:01:00.0] Family : NVE0
[    2.108563] nouveau  [   VBIOS][0000:01:00.0] checking PRAMIN for image...
[    2.108571] nouveau  [   VBIOS][0000:01:00.0] ... signature not found
[    2.108573] nouveau  [   VBIOS][0000:01:00.0] checking PROM for image...
[    2.149775] nouveau  [   VBIOS][0000:01:00.0] ... appears to be valid
[    2.149779] nouveau  [   VBIOS][0000:01:00.0] using image from PROM
[    2.149957] nouveau  [   VBIOS][0000:01:00.0] BIT signature found
[    2.149960] nouveau  [   VBIOS][0000:01:00.0] version 80.07.35.00.4f
[    2.150856] nouveau 0000:01:00.0: irq 33 for MSI/MSI-X
[    2.150869] nouveau  [     PMC][0000:01:00.0] MSI interrupts enabled
[    2.150933] nouveau  [     PFB][0000:01:00.0] RAM type: GDDR5
[    2.150935] nouveau  [     PFB][0000:01:00.0] RAM size: 1024 MiB
[    2.150937] nouveau  [     PFB][0000:01:00.0]    ZCOMP: 0 tags
[    2.811563] nouveau  [  PTHERM][0000:01:00.0] FAN control: PWM
[    2.811588] nouveau  [  PTHERM][0000:01:00.0] fan management: automatic
[    2.811634] nouveau  [  PTHERM][0000:01:00.0] internal sensor: yes
[    2.811711] nouveau  [     CLK][0000:01:00.0] 07: core 324 MHz memory 648 MHz 
[    2.811720] nouveau  [     CLK][0000:01:00.0] 0a: core 540 MHz memory 1620 MHz 
[    2.811727] nouveau  [     CLK][0000:01:00.0] 0f: core 1058 MHz memory 5000 MHz 
[    2.811872] nouveau  [     CLK][0000:01:00.0] --: core 324 MHz memory 648 MHz 
[    2.827731] nouveau  [     DRM] VRAM: 1024 MiB
[    2.827733] nouveau  [     DRM] GART: 1048576 MiB
[    2.827737] nouveau  [     DRM] TMDS table version 2.0
[    2.827738] nouveau  [     DRM] DCB version 4.0
[    2.827741] nouveau  [     DRM] DCB outp 00: 01000f02 00020030
[    2.827743] nouveau  [     DRM] DCB outp 01: 02000f00 00000000
[    2.827745] nouveau  [     DRM] DCB outp 02: 08011f82 00020030
[    2.827746] nouveau  [     DRM] DCB outp 03: 02022f62 00020010
[    2.827748] nouveau  [     DRM] DCB conn 00: 00001030
[    2.827750] nouveau  [     DRM] DCB conn 01: 00002131
[    2.827751] nouveau  [     DRM] DCB conn 02: 00010263
[    2.831931] nouveau  [     DRM] MM: using COPY for buffer copies
[    3.028691] nouveau  [     DRM] allocated 1920x1200 fb: 0x80000, bo ffff880621695800
[    3.028742] nouveau 0000:01:00.0: fb0: nouveaufb frame buffer device
[    3.028744] nouveau 0000:01:00.0: registered panic notifier
[    3.028747] [drm] Initialized nouveau 1.2.1 20120801 for 0000:01:00.0 on minor 0
[  757.564771] nouveau E[     CLK][0000:01:00.0] failed to raise voltage: -22
[  757.564778] nouveau E[     CLK][0000:01:00.0] error setting pstate 1: -22
[  802.350431] nouveau E[     CLK][0000:01:00.0] failed to raise voltage: -22
[  802.350439] nouveau E[     CLK][0000:01:00.0] error setting pstate 2: -22

Do the errors mean it didn't set?

# cat /sys/class/drm/card0/device/pstate
07: core 324 MHz memory 648 MHz
0a: core 540 MHz memory 1620 MHz AC DC *
0f: core 1058 MHz memory 5000 MHz
AC: core 324 MHz memory 1620 MHz

# echo 0f > /sys/class/drm/card0/device/pstate

# cat /sys/class/drm/card0/device/pstate
07: core 324 MHz memory 648 MHz
0a: core 540 MHz memory 1620 MHz
0f: core 1058 MHz memory 5000 MHz AC DC *
AC: core 324 MHz memory 5040 MHz

Is the :"AC" one supposed to be the current one?
Why does it say "5040 MHz" but 0f says "5000 MHz"?