Enable/Disable some sensors when Host On/Off

[Matt Spinler]

On 10/19/2020 10:23 AM, Thu Ba Nguyen wrote:
> Thanks for your reply Matt Spinler, Can you show me the discussion 
> threads? I also...
> This Message Is From an External Sender
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>
> Thanks for your reply Matt Spinler,
>
> Can you show me the discussion threads?

Sure: https://lists.ozlabs.org/pipermail/openbmc/2019-October/018967.html

>
> I also thought about the solution for that features:
> In the current hwmon we support GPIOCHIP + GPIO option which used to 
> enable sensors to read. In the hwmon code, we just set that pin and 
> wait before reading.
> I think we can support a similar option named GPIOENABLE + GPIOV. When 
> the status of Gpio pin defind in GPIOEANBLE match with GPIOV.
> That sensors will be read and update to Dbus.
> If not it will be removed from DBus until the GPIO pin math GPIOV.
> Maybe we can have many different solutions.

As Ed mentioned, I think a good direction to start with is how 
dbus-sensors handles it, so we  can have
common behavior.  I believe they look at the host state D-Bus property 
and still keep the sensor
on D-Bus even when power is off.

>
> If you don't mind, can you tell me how IBM supports that features?

We lucked out out in that the driver was only loaded when power was on.

>
> Regards.
> Thu Nguyen.
>
> On Mon, Oct 19, 2020 at 9:16 PM Matt Spinler <mspinler at linux.ibm.com 
> <mailto:mspinler at linux.ibm.com>> wrote:
>
>
>
>     On 10/18/2020 8:58 AM, Thu Ba Nguyen wrote:
>     > Dear, I'm supporting the host sensors for Ampere Computing LLC
>     > platform. We are...
>     > This Message Is From an External Sender
>     > This message came from outside your organization.
>     >
>     > Dear,
>     >
>     > I'm supporting the host sensors for Ampere Computing LLC platform.
>     > We are using phosphor-hwmon to update values of sensors and
>     monitoring
>     > sensors warning/errors base on threshold setting.
>     >
>     > There are some sensors which are turned off when host Off. It
>     can be
>     > the sensors reported by host or voltage/temperature/power sensors
>     >  which use the same power source with host.
>     >
>     > I researched in openBmc sensor-architecture documents but can't
>     find
>     > any option to enable/disable sensors base on one status or GPIO
>     pins.
>     > I can't use REMOVERCS.
>     >
>     > Research in phosphor-hwmon code, I don't see the answer too.
>     >
>     > Do we have any options/solution to Enable/Disable some sensors when
>     > Host On/Off?
>
>     Hi,
>     The phosphor-hwmon code doesn't support that yet.  It has been
>     discussed
>     before but nobody
>     has implemented it.
>
>     >
>     > Thanks.
>     > Thu Nguyen.
>