Bug 216204

Summary: ideapad-laptop: Testing for DYTC platform-profile support
Product: Drivers Reporter: John Vincent (git)
Component: Platform_x86Assignee: drivers_platform_x86 (drivers_platform_x86)
Status: RESOLVED ANSWERED    
Severity: low CC: jwrdegoede
Priority: P1    
Hardware: Intel   
OS: Linux   
Kernel Version: 5.18.9 Subsystem:
Regression: No Bisected commit-id:
Attachments: Decompiled DSDT of Lenovo IdeaPad 3 (14ITL05) - BIOS ver GCCN26WW

Description John Vincent 2022-07-05 03:01:02 UTC 
Created attachment 301332 [details]
Decompiled DSDT of Lenovo IdeaPad 3 (14ITL05) - BIOS ver GCCN26WW

Hello! I'm just curious on how do I test DYTC platform profiles compatibility with ideapad-laptop and my Lenovo laptop? I've merged the newest changes to the driver that adds (experimental) support to DYTC v4, but I couldn't find any concrete way to test it.

Even without the change applied (and boot option enabled), power-profiles-daemon is still present on GNOME and throttles the CPU speed. Is there any other way I can test for it? I currently am running the kernel on Fedora 36, if it helps.

I've attached the decompiled DSDT, and it seems to be very similar to https://bugzilla.kernel.org/show_bug.cgi?id=213297.

Hoping for your reply.
Thank you very much!
Comment 1 Hans de Goede 2022-09-19 09:01:24 UTC 
Sorry for the slow reply.

Note the kernel now allows enabling V4 DYTC support from the kernel commandline, by passing: ideapad_laptop.allow_v4_dytc=1 on the kernel commandline.

As for testing this:

1. Pass the kernel cmdline parameter
2. Check that switching the profile in GNOME results in the contents of
   /sys/firmware/acpi/platform_profile changing
3. Run a heavy workload, e.g. a make -j8 kernel compile
4. Monitor the power-consumption in powertop (while running from battery)
5. Change the profile

Step 5. should then result in significant changes of consumed power (this may take some minutes to register).

Without platform_profile support the GNOME setting only changes the pstate governer  profile, so things will ramp up slower. The actual platform_profile setting should change the RAPL values / should change the maximum energy consumption (programmable TPD) of the processor.

Note that this may only take effect when combined with running thermal-profiled with the experimental Intel DPTF support enabled.

Since there is not really a bug to fix here I'm going to close this bug report now.