power capping values on dbus

Adrian Ambrożewicz adrian.ambrozewicz at linux.intel.com
Tue May 26 23:01:06 AEST 2020

I don't think it's clear from your message what you are trying to achieve:
a) ability to expose power capping information as dbus-sensor just as 
read-only information
b) ability to set the cap through D-Bus interface

I suspect it's the former (just exposing data). If that's so I don't 
think you need any new interface at all. You could just add a 'Cap' 
sensor, eg Cpu0PowerCap and all the values fits nicely.

For latter, there already exist interface for configuring power capping 
however it doesn't specify properties for Min and Max values.


W dniu 5/26/2020 o 14:46, Zbyszek pisze:
> Hi everyone!
> I would like to expose on dbus values like min and max power capping.
> These values could be read from files provided by hwmon like:
>     power[1-*]_cap_max,
>     power[1-*]_cap_min
> which are describe here:
> https://www.kernel.org/doc/Documentation/hwmon/sysfs-interface
> I have noticed that this interface:
> https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/xyz/openbmc_project/Sensor/Value.interface.yaml
> is already exposing something like MinValue and MaxValue,
> but current implementation in dbus-sensors always sets these
> attributes to some const values.
> My understanding of the power capping values is that they could be used as these
> MinValue and MaxValue if hwmon provides them otherwise some default
> should be used as it is now.
> My questions:
> 1. Should I create a new interface for the capping readings?
> 2. Or should I extend the existing Value.interface.yaml with new
> attributes like MinCapValue, MaxCapValue?
> 3  Or the correct approach would be to read the cap values if provided
> and expose them under already existing MinValue, MaxValue?
> Regards,
> Zbigniew.

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