From: Artem Bityutskiy <dedekind1@gmail.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>, Sumit Gupta <sumitg@nvidia.com>
Cc: viresh.kumar@linaro.org, pierre.gondois@arm.com,
zhenglifeng1@huawei.com, 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
Subject: Re: [PATCH v7 4/7] ACPI: CPPC: add APIs and sysfs interface for min/max_perf
Date: Thu, 05 Feb 2026 15:10:09 +0200 [thread overview]
Message-ID: <acebbfddad686122c4aee9d1a87b048379dffbab.camel@gmail.com> (raw)
In-Reply-To: <CAJZ5v0gBHrGf4TpjqV+W5YynM+9_xWpepgrOiRegSYS9CvPV1g@mail.gmail.com>
On Tue, 2026-02-03 at 13:43 +0100, Rafael J. Wysocki wrote:
> On Thu, Jan 29, 2026 at 11:49 AM Sumit Gupta <sumitg@nvidia.com> wrote:
> >
> > Add cppc_get/set_min_perf() and cppc_get/set_max_perf() APIs to read and
> > write the MIN_PERF and MAX_PERF registers.
> >
> > Also add sysfs interfaces (min_perf, max_perf) in cppc_cpufreq driver
> > to expose these controls to userspace. The sysfs values are in frequency
> > (kHz) for consistency with other cpufreq sysfs files.
>
> But this is not cpufreq and it is not consistent.
Just my 2 cents to add:
CPPC and Intel CPUs don't use kHz for performance scaling. We should
avoid introducing additional kHz-based interfaces where possible, since
the performance units <-> kHz translation may become more complex over
time than today. Future implementations could involve non-linear
relationships and reduced accuracy. Minimizing kHz interfaces now may
help reduce future work.
Thanks,
Artem.
next prev parent reply other threads:[~2026-02-05 13:10 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
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 [this message]
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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