linux-kernel - Re: [PATCH 4/4] thermal: bang-bang governor: act on lower trip boundary

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Date:	Wed, 27 Apr 2016 14:54:26 -0700
From:	Eduardo Valentin <edubezval@...il.com>
To:	Caesar Wang <wxt@...k-chips.com>
Cc:	Heiko Stuebner <heiko@...ech.de>, dianders@...omium.org,
	briannorris@...gle.com, smbarber@...gle.com,
	linux-rockchip@...ts.infradead.org, dmitry.torokhov@...il.com,
	huangtao@...k-chips.com, eddie.cai@...k-chips.com,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Zhang Rui <rui.zhang@...el.com>, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] thermal: bang-bang governor: act on lower trip
 boundary

On Mon, Apr 25, 2016 at 11:02:47AM +0800, Caesar Wang wrote:
> From: Sascha Hauer <s.hauer@...gutronix.de>
> 
> With interrupt driven thermal zones we pass the lower and upper
> temperature on which shall be acted, so in the governor we have to act on
> the exact lower temperature to be consistent. Otherwise an interrupt maybe
> generated on the exact lower temperature, but the bang bang governor does
> not react.

What is the expected impact on polling driven zones that use bang bang
after this change?

> 
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> Signed-off-by: Caesar Wang <wxt@...k-chips.com>
> Cc: Zhang Rui <rui.zhang@...el.com>
> Cc: Eduardo Valentin <edubezval@...il.com>
> Cc: linux-pm@...r.kernel.org
> 
> ---
> 
>  drivers/thermal/gov_bang_bang.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/thermal/gov_bang_bang.c b/drivers/thermal/gov_bang_bang.c
> index 70836c5..9d1dfea 100644
> --- a/drivers/thermal/gov_bang_bang.c
> +++ b/drivers/thermal/gov_bang_bang.c
> @@ -59,7 +59,7 @@ static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
>  		if (instance->target == 0 && tz->temperature >= trip_temp)
>  			instance->target = 1;
>  		else if (instance->target == 1 &&
> -				tz->temperature < trip_temp - trip_hyst)
> +				tz->temperature <= trip_temp - trip_hyst)
>  			instance->target = 0;
>  
>  		dev_dbg(&instance->cdev->device, "target=%d\n",
> -- 
> 1.9.1
>