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[2001:1c00:c0c:fe00:6c10:fbf3:14c4:884c]) by smtp.gmail.com with ESMTPSA id r3sm2768715edw.42.2020.10.28.04.54.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Oct 2020 04:54:42 -0700 (PDT) Subject: Re: [PATCH] Documentation: Add documentation for new platform_profile sysfs attribute To: Mark Pearson Cc: dvhart@infradead.org, mgross@linux.intel.com, mario.limonciello@dell.com, eliadevito@gmail.com, hadess@hadess.net, bberg@redhat.com, linux-pm@vger.kernel.org, linux-acpi@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org References: <20201027164219.868839-1-markpearson@lenovo.com> From: Hans de Goede Message-ID: <8749d17c-4d0b-5c29-a8c9-4a6704b422d6@redhat.com> Date: Wed, 28 Oct 2020 12:54:41 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 MIME-Version: 1.0 In-Reply-To: <20201027164219.868839-1-markpearson@lenovo.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: platform-driver-x86@vger.kernel.org Hi, A few minor nitpicks below, mostly stuff which I missed before, sorry. I suggest you make v2 part of the series where you actually add the drivers/acpi/... and the thinkpad_acpi.c bits to implement this. On 10/27/20 5:42 PM, Mark Pearson wrote: > From: Hans de Goede > > On modern systems the platform performance, temperature, fan and other > hardware related characteristics are often dynamically configurable. The > profile is often automatically adjusted to the load by somei s/somei/some/ > automatic-mechanism (which may very well live outside the kernel). > > These auto platform-adjustment mechanisms often can be configured with > one of several 'platform-profiles', with either a bias towards low-power > consumption or towards performance (and higher power consumption and > thermals). I think it is better to also drop the " (and higher power consumption and thermals)" bit here (and below) like you did for the cool and quiet parts. Regards, Hans > Introduce a new platform_profile sysfs API which offers a generic API for > selecting the performance-profile of these automatic-mechanisms. > > Co-developed-by: Mark Pearson > Signed-off-by: Mark Pearson > Signed-off-by: Hans de Goede > --- > Changes in V1: > - Moved from RFC to proposed patch > - Added cool profile as requested > - removed extra-profiles as no longer relevant > > .../ABI/testing/sysfs-platform_profile | 66 +++++++++++++++++++ > 1 file changed, 66 insertions(+) > create mode 100644 Documentation/ABI/testing/sysfs-platform_profile > > diff --git a/Documentation/ABI/testing/sysfs-platform_profile b/Documentation/ABI/testing/sysfs-platform_profile > new file mode 100644 > index 000000000000..240bd3d7532b > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-platform_profile > @@ -0,0 +1,66 @@ > +Platform-profile selection (e.g. /sys/firmware/acpi/platform_profile) > + > +On modern systems the platform performance, temperature, fan and other > +hardware related characteristics are often dynamically configurable. The > +profile is often automatically adjusted to the load by some > +automatic-mechanism (which may very well live outside the kernel). > + > +These auto platform-adjustment mechanisms often can be configured with > +one of several 'platform-profiles', with either a bias towards low-power > +consumption or towards performance (and higher power consumption and > +thermals). > + > +The purpose of the platform_profile attribute is to offer a generic sysfs > +API for selecting the platform-profile of these automatic-mechanisms. > + > +Note that this API is only for selecting the platform-profile, it is > +NOT a goal of this API to allow monitoring the resulting performance > +characteristics. Monitoring performance is best done with device/vendor > +specific tools such as e.g. turbostat. > + > +Specifically when selecting a high-performance profile the actual achieved > +performance may be limited by various factors such as: the heat generated > +by other components, room temperature, free air flow at the bottom of a > +laptop, etc. It is explicitly NOT a goal of this API to let userspace know > +about any sub-optimal conditions which are impeding reaching the requested > +performance level. > + > +Since numbers are a rather meaningless way to describe platform-profiles > +this API uses strings to describe the various profiles. To make sure that > +userspace gets a consistent experience when using this API this API > +document defines a fixed set of profile-names. Drivers *must* map their > +internal profile representation/names onto this fixed set. > + > +If for some reason there is no good match when mapping then a new profile-name > +may be added. Drivers which wish to introduce new profile-names must: > +1. Have very good reasons to do so. > +2. Add the new profile-name to this document, so that future drivers which also > + have a similar problem can use the same name. > + > +What: /sys/firmware/acpi/platform_profile_choices > +Date: October 2020 > +Contact: Hans de Goede > +Description: > + Reading this file gives a space separated list of profiles > + supported for this device. > + > + Drivers must use the following standard profile-names: > + > + low-power: Emphasises low power consumption > + cool: Emphasises cooler operation > + quiet: Emphasises quieter operation > + balanced: Balance between low power consumption > + and performance > + performance: Emphasises performance (and may lead to > + higher temperatures and fan speeds) > + > + Userspace may expect drivers to offer at least several of these > + standard profile-names. > + > +What: /sys/firmware/acpi/platform_profile > +Date: October 2020 > +Contact: Hans de Goede > +Description: > + Reading this file gives the current selected profile for this > + device. Writing this file with one of the strings from > + available_profiles changes the profile to the new value. >