Enable/Disable some sensors when Host On/Off

[Matt Spinler]

On 10/20/2020 9:18 AM, Patrick Williams wrote:
> On Tue, Oct 20, 2020 at 08:46:30AM -0500, Matt Spinler wrote:
>>
>> On 10/19/2020 10:23 AM, Thu Ba Nguyen wrote:
>>> 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.
> ...
>>> 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.
>>
> Hi Thu,
>
> Is this something you could do similarly?  Rather than have the driver
> understand the GPIO directly you can trigger a phosphor-gpio-monitor
> service that does a 'bind' / 'unbind' to dynamically enable and disable
> the hwmon driver?
>
> Matt, is that how you have the driver configured to load / unload (I
> assume your case is for the OCC).

We use a slightly different mechanism since we need to wait for the host
to tell us the device is running (yea it's the OCC), but same general idea.

>