linux-kernel - Re: [PATCH] drivers: thermal: Reset previous low and high trip during thermal zone init

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Date:   Fri, 5 Nov 2021 14:48:53 -0400
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     Manaf Meethalavalappu Pallikunhi <manafm@...eaurora.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers: thermal: Reset previous low and high trip during
 thermal zone init



On 11/2/21 4:00 PM, Manaf Meethalavalappu Pallikunhi wrote:
> During the suspend is in process, thermal_zone_device_update bails out
> thermal zone re-evaluation for any sensor trip violation without
> setting next valid trip to that sensor. It assumes during resume
> it will re-evaluate same thermal zone and update trip. But when it is
> in suspend temperature goes down and on resume path while updating
> thermal zone if temperature is less than previously violated trip,
> thermal zone set trip function evaluates the same previous high and
> previous low trip as new high and low trip. Since there is no change
> in high/low trip, it bails out from thermal zone set trip API without
> setting any trip. It leads to a case where sensor high trip or low
> trip is disabled forever even though thermal zone has a valid high
> or low trip.
> 
> During thermal zone device init, reset thermal zone previous high
> and low trip. It resolves above mentioned scenario.
> 
> Signed-off-by: Manaf Meethalavalappu Pallikunhi <manafm@...eaurora.org>

Reviewed-by: Thara Gopinath <thara.gopinath@...aro.org>

-- 
Warm Regards
Thara (She/Her/Hers)

> ---
>   drivers/thermal/thermal_core.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 21db445..2b7a0b4 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -477,6 +477,8 @@ static void thermal_zone_device_init(struct thermal_zone_device *tz)
>   {
>   	struct thermal_instance *pos;
>   	tz->temperature = THERMAL_TEMP_INVALID;
> +	tz->prev_low_trip = -INT_MAX;
> +	tz->prev_high_trip = INT_MAX;
>   	list_for_each_entry(pos, &tz->thermal_instances, tz_node)
>   		pos->initialized = false;
>   }
>