From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3838E34DCFE; Thu, 13 Nov 2025 12:41:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763037687; cv=none; b=p4hqVoprkvjeQZgtLqMXdAEzaXDCiapcTNSb1M7DBlwbjkKVb5WZ+R+4QgXDcZBzTidmgBFgYlSnoNtZmOJZ7V1JhW0ATFsnZyFT9yp3Xze0RuaBsB/xZQKIJYd2HRAP+Bb6PE00I/vVcjnSArRZI9mX87fL1229oxROnG6oJis= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763037687; c=relaxed/simple; bh=XaTNNB/CqGz+V+OMzj/mIjV+mLYVDACn92ZqVORRSbQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gGQtwWGpvSRE3rZqCBr6YsDBZ3xf5YJjR/31CnDfvrFvoKlulf3pdhMFqyaf9pndTijPryqI1+Sl8BNoznQ79X6gyczOnvN/SLxfGwvlpxMcM11y5AGpJAYr+JPoV+i0nTzbgeRd4q47eDfelLUNoyB4upBvvsRJxB+jHgOuBv4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C26B012FC; Thu, 13 Nov 2025 04:41:16 -0800 (PST) Received: from localhost (ionvoi01-desktop.cambridge.arm.com [10.2.80.58]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 026C73F5A1; Thu, 13 Nov 2025 04:41:24 -0800 (PST) Date: Thu, 13 Nov 2025 12:41:19 +0000 From: Ionela Voinescu To: Sumit Gupta Cc: rafael@kernel.org, viresh.kumar@linaro.org, lenb@kernel.org, robert.moore@intel.com, corbet@lwn.net, pierre.gondois@arm.com, zhenglifeng1@huawei.com, 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 v4 6/8] cpufreq: CPPC: Add sysfs for min/max_perf and perf_limited Message-ID: References: <20251105113844.4086250-1-sumitg@nvidia.com> <20251105113844.4086250-7-sumitg@nvidia.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251105113844.4086250-7-sumitg@nvidia.com> Hi, On Wednesday 05 Nov 2025 at 17:08:42 (+0530), Sumit Gupta wrote: > Add sysfs interfaces for Minimum Performance, Maximum Performance > and Performance Limited Register in the cppc_cpufreq driver. > > Reviewed-by: Randy Dunlap > Signed-off-by: Sumit Gupta > --- > .../ABI/testing/sysfs-devices-system-cpu | 46 +++++++++++++++++++ > 1 file changed, 46 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu > index 8aed6d94c4cd..6f1f70696000 100644 > --- a/Documentation/ABI/testing/sysfs-devices-system-cpu > +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu > @@ -327,6 +327,52 @@ Description: Energy performance preference > > This file is only present if the cppc-cpufreq driver is in use. > > +What: /sys/devices/system/cpu/cpuX/cpufreq/min_perf > +Date: December 2025 > +Contact: linux-pm@vger.kernel.org > +Description: Minimum Performance Frequency > + > + Read/write a frequency value in kHz from/to this file. This > + file conveys the minimum performance level (as frequency) at > + which the platform may run. The frequency value is internally > + converted to a performance value and must correspond to a > + performance level in the range [Lowest Performance, Highest > + Performance], inclusive. The minimum must be less than or equal > + to the maximum performance. The performance range can be checked > + from nodes: > + /sys/devices/system/cpu/cpuX/acpi_cppc/highest_perf > + /sys/devices/system/cpu/cpuX/acpi_cppc/lowest_perf I think information on highest/lowest performance is irrelevant here. If the user is expected to provide a frequency value, it should only care about it being in the range [cpuinfo_min_freq, cpuinfo_max_freq]. I think ideally all of these controls (auto-select, EPP, min, max, etc.) would have been better placed under /sys/devices/system/cpu/cpuX/acpi_cppc, but I suppose the intention was/is to have all performance related controls under cpufreq. But that means that the user should not be concerned about the underlying CPPC scale and only use /sys/devices/system/cpu/cpuX/acpi_cppc for information purposes. Thanks, Ionela. > + > + This file is only present if the cppc-cpufreq driver is in use. > + > +What: /sys/devices/system/cpu/cpuX/cpufreq/max_perf > +Date: December 2025 > +Contact: linux-pm@vger.kernel.org > +Description: Maximum Performance Frequency > + > + Read/write a frequency value in kHz from/to this file. This > + file conveys the maximum performance level (as frequency) at > + which the platform may run. The frequency value is internally > + converted to a performance value and must correspond to a > + performance level in the range [Lowest Performance, Highest > + Performance], inclusive. The performance range can be checked > + from nodes: > + /sys/devices/system/cpu/cpuX/acpi_cppc/highest_perf > + /sys/devices/system/cpu/cpuX/acpi_cppc/lowest_perf > + > + This file is only present if the cppc-cpufreq driver is in use. > + > +What: /sys/devices/system/cpu/cpuX/cpufreq/perf_limited > +Date: December 2025 > +Contact: linux-pm@vger.kernel.org > +Description: Performance Limited > + > + Read/write a 32 bits value from/to this file. This file indicates > + to OSPM that an unpredictable event has limited processor > + performance, and the delivered performance may be less than > + desired/minimum performance. > + > + This file is only present if the cppc-cpufreq driver is in use. > > What: /sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1} > Date: August 2008 > -- > 2.34.1 >