Intel GPU frequency is not restored if not set

[ilovelinux]

[x] I've read and accepted the Bug Reporting Howto
[x] I've provided all required tlp-stat outputs via Gist (see below)

Describe the bug

Context

• I'm using xe drivers.
• I read https://linrunner.de/tlp/settings/graphics.html#intel-gpu-min-max-boost-freq-on-ac-bat
• I guessed =0 meant Auto.
• I configured GPU frequency for BAT and nothing for AC.

Config:

INTEL_GPU_POWER_PROFILE_ON_BAT = "power_saving"; # <- This is restored to `base` as described.
INTEL_GPU_MIN_FREQ_ON_BAT = 100;
INTEL_GPU_MAX_FREQ_ON_BAT = 600;
INTEL_GPU_BOOST_FREQ_ON_BAT = 600;
# == Additional configuration to restore "default" GPU values - added after this behavior has been discovered
# INTEL_GPU_MIN_FREQ_ON_AC = 100;
# INTEL_GPU_MAX_FREQ_ON_AC = 1250;
# INTEL_GPU_BOOST_FREQ_ON_AC = 1250;

Expected behavior

• I expected that =0 would mean "restore to GPU defaults" or something like that.
• GPU configuration is left to BAT values.
• If that's the intended behavior, I think the doc could be improved.
• If that's not the intended behavior, that's a bug.

To Reproduce

Steps to reproduce the unexpected behavior:

• Lower the clock speed for BAT - set nothing for AC.
• Switch from AC to BAT.
• Switch back from BAT to AC.

tlp-stat

Additional context

Add any other context about the problem here.

[ilovelinux]

Digging in the code I found this:

TLP/tlp.conf.in

Lines 395 to 410 in 5abc687

	# Set the min/max/turbo frequency for the Intel GPU.
	# Parameters actually used depend on the driver:
	# - i915 driver supports min, max and turbo(boost) frequency
	# - xe driver supports min and max frequency only
	# - Frequencies must always be specified for all profiles
	# Default: <none>
	#INTEL_GPU_MIN_FREQ_ON_PRF=0
	#INTEL_GPU_MIN_FREQ_ON_BAL=0
	#INTEL_GPU_MIN_FREQ_ON_SAV=0
	#INTEL_GPU_MAX_FREQ_ON_PRF=0
	#INTEL_GPU_MAX_FREQ_ON_BAL=0
	#INTEL_GPU_MAX_FREQ_ON_SAV=0
	#INTEL_GPU_BOOST_FREQ_ON_PRF=0
	#INTEL_GPU_BOOST_FREQ_ON_BAL=0
	#INTEL_GPU_BOOST_FREQ_ON_SAV=0

L399 is the interesting part:

TLP/tlp.conf.in

Line 399 in 5abc687

# - Frequencies must always be specified for all profiles

That's the warn I would have like to find in the documentation 😄

---

I just checked the git blame and the commit is 5-days old! I think this is gonna land in the next release then. Thank you! Closing 😄

[linrunner]

This applies not only to this feature but to all of them, which is why it’s mentioned at the head of tlp.conf and at the doc site. The latter may contain more recent information that becomes available after a release. So always check there first. I don’t release a new version just for minor tweaks to tlp.conf.

The reason why configuration of all profiles is required is quite simple: TLP never “stores” a tunable state, so it can’t “restore” anything either. Instead every time when activating a profile it applies configured settings (either explicitly by the user or implicitly by a default).

[ilovelinux]

The latter may contain more recent information that becomes available after a release. So always check there first. I don’t release a new version just for minor tweaks to tlp.conf.

Makes sense, thank you! 😄

The reason why configuration of all profiles is required is quite simple: TLP never “stores” a tunable state, so it can’t “restore” anything either. Instead every time when activating a profile it applies configured settings (either explicitly by the user or implicitly by a default).

I know that TLP never stores anything, but I thought there was some kind of default driver/hardware-side e.g.:

/sys/class/drm/card0/device/tile0/gt0/freq0/rpn_freq         =    100 [MHz] (GPU min)
/sys/class/drm/card0/device/tile0/gt0/freq0/rpe_freq         =    600 [MHz] (GPU efficient)
/sys/class/drm/card0/device/tile0/gt0/freq0/rp0_freq         =   1250 [MHz] (GPU max)

That new documentation line should be enough to warn the user about ""unexpected"" behaviors like this.

Do you think using rpn_freq and rp0_freq by default would be possible? I don't know if that's available on every GPU and for both i915 and xe drivers.