From: Sumit Gupta <sumitg@nvidia.com>
To: Russell Haley <yumpusamongus@gmail.com>,
"zhenglifeng (A)" <zhenglifeng1@huawei.com>,
pierre.gondois@arm.com, "Rafael J. Wysocki" <rafael@kernel.org>
Cc: rafael@kernel.org, viresh.kumar@linaro.org,
ionela.voinescu@arm.com, lenb@kernel.org, robert.moore@intel.com,
corbet@lwn.net, rdunlap@infradead.org, ray.huang@amd.com,
gautham.shenoy@amd.com, mario.limonciello@amd.com,
perry.yuan@amd.com, zhanjie9@hisilicon.com,
linux-pm@vger.kernel.org, linux-acpi@vger.kernel.org,
linux-doc@vger.kernel.org, acpica-devel@lists.linux.dev,
linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org,
treding@nvidia.com, jonathanh@nvidia.com, vsethi@nvidia.com,
ksitaraman@nvidia.com, sanjayc@nvidia.com, nhartman@nvidia.com,
bbasu@nvidia.com, sumitg@nvidia.com
Subject: Re: [PATCH v7 4/7] ACPI: CPPC: add APIs and sysfs interface for min/max_perf
Date: Tue, 3 Feb 2026 15:11:20 +0530 [thread overview]
Message-ID: <944fc140-e5c5-425f-a6ad-883e87eed8a3@nvidia.com> (raw)
In-Reply-To: <74f3e6cf-7c13-43e6-a8f6-2b46184b8ad6@gmail.com>
>>> Hi Sumit,
>>>
>>> I am thinking that maybe it is better to call these two sysfs interface
>>> 'min_freq' and 'max_freq' as users read and write khz instead of raw
>>> value.
>> Thanks for the suggestion.
>> Kept min_perf/max_perf to match the CPPC register names
>> (MIN_PERF/MAX_PERF), making it clear to users familiar with
>> CPPC what's being controlled.
>> The kHz unit is documented in the ABI.
>>
>> Thank you,
>> Sumit Gupta
> On my x86 machine with kernel 6.18.5, the kernel is exposing raw values:
>
>> grep . /sys/devices/system/cpu/cpu0/acpi_cppc/*
> /sys/devices/system/cpu/cpu0/acpi_cppc/feedback_ctrs:ref:342904018856568
> del:437439724183386
> /sys/devices/system/cpu/cpu0/acpi_cppc/guaranteed_perf:63
> /sys/devices/system/cpu/cpu0/acpi_cppc/highest_perf:88
> /sys/devices/system/cpu/cpu0/acpi_cppc/lowest_freq:0
> /sys/devices/system/cpu/cpu0/acpi_cppc/lowest_nonlinear_perf:36
> /sys/devices/system/cpu/cpu0/acpi_cppc/lowest_perf:1
> /sys/devices/system/cpu/cpu0/acpi_cppc/nominal_freq:3900
> /sys/devices/system/cpu/cpu0/acpi_cppc/nominal_perf:62
> /sys/devices/system/cpu/cpu0/acpi_cppc/reference_perf:62
> /sys/devices/system/cpu/cpu0/acpi_cppc/wraparound_time:18446744073709551615
>
> It would be surprising for a nearby sysfs interface with very similar
> names to use kHz instead.
>
> Thanks,
>
> Russell Haley
I can rename to either of the below:
- min/max_freq: might be confused with scaling_min/max_freq.
- min/max_perf_freq: keeps the CPPC register association clear.
Rafael, Any preferences here?
Thank you,
Sumit Gupta
next prev parent reply other threads:[~2026-02-03 9:41 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-29 10:48 [PATCH v7 0/7] Enhanced autonomous selection and improvements Sumit Gupta
2026-01-29 10:48 ` [PATCH v7 1/7] ACPI: CPPC: Add cppc_get_perf() API to read performance controls Sumit Gupta
2026-01-29 10:48 ` [PATCH v7 2/7] ACPI: CPPC: Warn on missing mandatory DESIRED_PERF register Sumit Gupta
2026-01-29 10:48 ` [PATCH v7 3/7] ACPI: CPPC: Extend cppc_set_epp_perf() for FFH/SystemMemory Sumit Gupta
2026-01-29 10:48 ` [PATCH v7 4/7] ACPI: CPPC: add APIs and sysfs interface for min/max_perf Sumit Gupta
2026-01-31 4:06 ` zhenglifeng (A)
2026-01-31 13:58 ` Sumit Gupta
2026-02-03 1:36 ` Russell Haley
2026-02-03 9:41 ` Sumit Gupta [this message]
2026-02-03 12:45 ` Rafael J. Wysocki
2026-02-03 12:54 ` Rafael J. Wysocki
2026-02-03 14:31 ` Sumit Gupta
2026-02-03 20:24 ` Rafael J. Wysocki
2026-02-03 20:28 ` Mario Limonciello
2026-02-04 9:51 ` Sumit Gupta
2026-02-04 13:02 ` Rafael J. Wysocki
2026-02-05 19:21 ` Sumit Gupta
2026-02-05 19:27 ` Rafael J. Wysocki
2026-02-03 12:43 ` Rafael J. Wysocki
2026-02-03 12:50 ` Rafael J. Wysocki
2026-02-05 13:10 ` Artem Bityutskiy
2026-01-29 10:48 ` [PATCH v7 5/7] ACPI: CPPC: add APIs and sysfs interface for perf_limited Sumit Gupta
2026-01-29 10:48 ` [PATCH v7 6/7] cpufreq: CPPC: Add sysfs for min/max_perf and perf_limited Sumit Gupta
2026-01-29 10:48 ` [PATCH v7 7/7] cpufreq: CPPC: Update cached perf_ctrls on sysfs write Sumit Gupta
2026-01-30 8:23 ` [PATCH v7 0/7] Enhanced autonomous selection and improvements Pierre Gondois
2026-01-31 2:58 ` zhenglifeng (A)
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