Re: [PATCH 1/3] thermal: core: Add indication for userspace usage

[Kai-Heng Feng]

> On Dec 1, 2020, at 02:39, Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> wrote:
> 
> On Tue, 2020-12-01 at 02:22 +0800, Kai-Heng Feng wrote:
>>> On Dec 1, 2020, at 02:13, Srinivas Pandruvada <
>>> srinivas.pandruvada@xxxxxxxxxxxxxxx> wrote:
>> 
>> [snipped] 
>> 
>>>>> What about creating an new callback
>>>>> 
>>>>> enum thermal_trip_status {
>>>>> 	THERMAL_TRIP_DISABLED = 0,
>>>>> 	THERMAL_TRIP_ENABLED,
>>>>> };
>>>>> 
>>>>> int get_trip_status(struct thermal_zone_device *, int trip,
>>>>> enum
>>>>> thermal_trip_status *state);
>>>>> 
>>>>> Then in 
>>>>> static void handle_thermal_trip(struct thermal_zone_device *tz,
>>>>> int
>>>>> trip)
>>>>> {
>>>>> 
>>>>> /* before tz->ops->get_trip_temp(tz, trip, &trip_temp); */
>>>>> if (tz->ops->get_trip_status) {
>>>>> 	enum thermal_trip_status *status;
>>>>> 
>>>>> 	if (!tz->ops->get_trip_status(tz, trip, &status)) {
>>>>> 		if (status == THERMAL_TRIP_DISABLED)
>>>>> 			return;	
>>>>> 	}
>>>>> }
>>>>> ...
>>>>> ...
>>>>> 
>>>>> }
>>>>> 
>>>>> 
>>>>> This callback will help the cases:
>>>>> - Allows drivers to selectively disable certain trips during
>>>>> init
>>>>> state
>>>>> or system resume where there can be spikes or always. int340x
>>>>> drivers
>>>>> can disable always.
>>>> 
>>>> This sounds really great. This is indeed can happen on system
>>>> resume,
>>>> before userspace process thaw.
>>>> 
>>>>> - Still give options for drivers to handle critical trip even
>>>>> if
>>>>> they
>>>>> are bound to user space governors. User space process may be
>>>>> dead,
>>>>> so
>>>>> still allow kernel to process graceful shutdown
>>>> 
>>>> To make the scenario happen, do we need a new sysfs to let
>>>> usespace
>>>> enable it with THERMAL_TRIP_ENABLED?
>>> This should be drivers call not user space.
>> 
>> Understood. So after thermal_zone_device_register(), the driver can
>> decide to what to return on get_trip_temp().
> get_trip_status()
> 
>> Let me work on a new patch if there's no other concern.
> Better to wait for confirmation from Daniel and others.

Daniel,

Do you like Srinivas' proposed solution?

I hope we can find a solution in upstream kernel soon.

Kai-Heng

> 
> Thanks,
> Srinivas
> 
>> 
>> Kai-Heng
>> 
>>> Thanks,
>>> Srinivas