On Mon, Oct 19, 2020 at 8:43 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > > Hi, > > On 10/18/20 2:31 PM, Rafael J. Wysocki wrote: > > On Sun, Oct 18, 2020 at 11:41 AM Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > >> > >> Hi, > >> > >> On 10/16/20 4:51 PM, Rafael J. Wysocki wrote: > >>> On Fri, Oct 16, 2020 at 1:11 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > >>>> > >>>> <note folding the 2 threads we are having on this into one, adding every one from both threads to the Cc> > >>>> > >>>> Hi, > >>>> > >>>> On 10/14/20 5:42 PM, Rafael J. Wysocki wrote: > >>>>> On Wed, Oct 14, 2020 at 4:06 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > >>>>>> On 10/14/20 3:33 PM, Rafael J. Wysocki wrote: > >>>> > >>>> <snip> > >>>> > >>>>>>> First, a common place to register a DPTF system profile seems to be > >>>>>>> needed and, as I said above, I wouldn't expect more than one such > >>>>>>> thing to be present in the system at any given time, so it may be > >>>>>>> registered along with the list of supported profiles and user space > >>>>>>> will have to understand what they mean. > >>>>>> > >>>>>> Mostly Ack, I would still like to have an enum for DPTF system > >>>>>> profiles in the kernel and have a single piece of code map that > >>>>>> enum to profile names. This enum can then be extended as > >>>>>> necessary, but I want to avoid having one driver use > >>>>>> "Performance" and the other "performance" or one using > >>>>>> "performance-balanced" and the other "balanced-performance", etc. > >>>>>> > >>>>>> With the goal being that new drivers use existing values from > >>>>>> the enum as much as possible, but we extend it where necessary. > >>>>> > >>>>> IOW, just a table of known profile names with specific indices assigned to them. > >>>> > >>>> Yes. > >>>> > >>>>> This sounds reasonable. > >>>>> > >>>>>>> Second, irrespective of the above, it may be useful to have a > >>>>>>> consistent way to pass performance-vs-power preference information > >>>>>>> from user space to different parts of the kernel so as to allow them > >>>>>>> to adjust their operation and this could be done with a system-wide > >>>>>>> power profile attribute IMO. > >>>>>> > >>>>>> I agree, which is why I tried to tackle both things in one go, > >>>>>> but as you said doing both in 1 API is probably not the best idea. > >>>>>> So I believe we should park this second issue for now and revisit it > >>>>>> when we find a need for it. > >>>>> > >>>>> Agreed. > >>>>> > >>>>>> Do you have any specific userspace API in mind for the > >>>>>> DPTF system profile selection? > >>>>> > >>>>> Not really. > >>>> > >>>> So before /sys/power/profile was mentioned, but that seems more like > >>>> a thing which should have a set of fixed possible values, iow that is > >>>> out of scope for this discussion. > >>> > >>> Yes. > >>> > >>>> Since we all seem to agree that this is something which we need > >>>> specifically for DPTF profiles maybe just add: > >>>> > >>>> /sys/power/dptf_current_profile (rw) > >>>> /sys/power/dptf_available_profiles (ro) > >>>> > >>>> (which will only be visible if a dptf-profile handler > >>>> has been registered) ? > >>>> > >>>> Or more generic and thus better (in case other platforms > >>>> later need something similar) I think, mirror the: > >>>> > >>>> /sys/bus/cpu/devices/cpu#/cpufreq/energy_performance_* bits > >>>> for a system-wide energy-performance setting, so we get: > >>>> > >>>> /sys/power/energy_performance_preference > >>>> /sys/power/energy_performance_available_preferences > >>> > >>> But this is not about energy vs performance only in general, is it? > >>> > >>>> (again only visible when applicable) ? > >>>> > >>>> I personally like the second option best. > >>> > >>> But I would put it under /sys/firmware/ instead of /sys/power/ and I > >>> would call it something like platform_profile (and > >>> platform_profile_choices or similar). > >> > >> Currently we only have dirs under /sys/firmware: > >> > >> [hans@x1 ~]$ ls /sys/firmware > >> acpi dmi efi memmap > >> > >> But we do have /sys/firmware/apci/pm_profile: > >> > >> Documentation/ABI/stable/sysfs-acpi-pmprofile > >> > >> What: /sys/firmware/acpi/pm_profile > >> Date: 03-Nov-2011 > >> KernelVersion: v3.2 > >> Contact: linux-acpi@xxxxxxxxxxxxxxx > >> Description: The ACPI pm_profile sysfs interface exports the platform > >> power management (and performance) requirement expectations > >> as provided by BIOS. The integer value is directly passed as > >> retrieved from the FADT ACPI table. > >> Values: For possible values see ACPI specification: > >> 5.2.9 Fixed ACPI Description Table (FADT) > >> Field: Preferred_PM_Profile > >> > >> Currently these values are defined by spec: > >> 0 Unspecified > >> 1 Desktop > >> 2 Mobile > >> 3 Workstation > >> 4 Enterprise Server > >> ... > >> > >> Since all platforms which we need this for are ACPI based > >> (and the involved interfaces are also all ACPI interfaces) > >> how about: > >> > >> /sys/firmware/acpi/platform_profile > >> /sys/firmware/acpi/platform_profile_choices > >> > >> ? > >> > >> I think this goes nice together with /sys/firmware/acpi/pm_profile > >> although that is read-only and this is a read/write setting. > >> > >> Rafel, would: > >> > >> /sys/firmware/acpi/platform_profile > >> /sys/firmware/acpi/platform_profile_choices > >> > >> work for you ? > > > > Yes, it would. > > Great. So I think hat means that we have the most important part > for moving forward with this. > > So I guess the plan for this now looks something like this. > > 1. Rewrite my API docs RFC to update it for the new /sys/firmware/acpi/platform_profile[_choices] > plan (should be easy and a bunch of stuff like the "type" bit can just be dropped) > > 2. Add code somewhere under drivers/acpi which allows code from else where > to register itself as platform_profile handler/provider. Sounds good to me. > Rafael, any suggestions / preference for where this should be added under > drivers/acpi ? In a new .c file perhaps ? Yes, that would be most suitable IMV. > 3.1 Use the code from 2 to add support for platform-profile selection in > thinkpad_acpi (something for me or Mark Pearson) to do > 3.2 Use the code from 2 to add support for platform-profile selection > to hp-wmi > 3.3 (and to other drivers in the future). Right.
