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SolidRun / lx2160a_uefi

Parent build repository for generating UEFI firmware for the LX2160a
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cpufreq on ACPI #25

Open ndoo opened 2 months ago

ndoo commented 2 months ago

Hi there, does DVFS work on ACPI with qoriq-cpufreq? qoriq-cpufreq expects DT bindings at fsl,lx2160a-clockgen but I'm not sure how it translates to UEFI+ACPI.

Presumably, cpufreq doesn't work as the cpufreq driver nodes don't seem to be in /sys

jnettlet commented 1 month ago

DVFS does not work with ACPI. It was originally implemented in an older ACPI method, which is now deprecated and replaced CPPC. From my testing there is virtually no benefit on the LX2160a (maybe 1W Max) when clocking down the cores to lower values. Since the target market for the platform generally requires the lowest latency and has a pretty standard workload we have no plans to implement this feature.

From: Andrew Yong @.> Sent: Tuesday, October 1, 2024 5:57 PM To: SolidRun/lx2160a_uefi @.> Cc: Subscribed @.***> Subject: [SolidRun/lx2160a_uefi] cpufreq on ACPI (Issue #25)

Hi there, does DVFS work on ACPI with qoriq-cpufreq? qoriq-cpufreq expects DT bindings at fsl,lx2160a-clockgen but I'm not sure how it translates to UEFI+ACPI.

Presumably, cpufreq doesn't work as the cpufreq driver nodes don't seem to be in /sys

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ndoo commented 1 month ago

Thanks for the reply and explanation.

In that case, can clock frequencies be exposed even if they are fixed/incorrect, as it seems to break popular visualization tools like s-tui and glances?

jnettlet commented 1 month ago

A max clock speed is exposed in the smbios tables as per the SystemReady ES spec. You can use dmidecode to get the data.

Handle 0x1008, DMI type 4, 50 bytes Processor Information       Socket Designation: BGA-1156       Type: Central Processor       Family: ARM       Manufacturer: NXP       ID: 00 00 00 00 00 00 00 00       Version: Cortex-A72       Voltage: 0.0 V       External Clock: 100 MHz       Max Speed: 2200 MHz       Current Speed: 2000 MHz       Status: Populated, Enabled       Upgrade: Other       L1 Cache Handle: 0x1000       L2 Cache Handle: 0x1002       L3 Cache Handle: Not Provided       Serial Number: Not Specified       Asset Tag: Not Specified       Part Number: 0xd08       Core Count: 16       Core Enabled: 16       Characteristics:             64-bit capable             Multi-Core             Execute Protection             Enhanced Virtualization             Power/Performance Control

From: Andrew Yong @.> Sent: Wednesday, October 2, 2024 3:42 PM To: SolidRun/lx2160a_uefi @.> Cc: Jon Nettleton @.>; Comment @.> Subject: Re: [SolidRun/lx2160a_uefi] cpufreq on ACPI (Issue #25)

Thanks for the reply and explanation.

In that case, can clock frequencies be exposed even if they are fixed/incorrect, as it seems to break popular visualization tools like s-tui and glances?

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