Re: [PATCH] acerhdf: Fix fan activation with new thermal governor

[Zhang Rui <rui.zhang@intel.com>]

On Sun, 2013-02-24 at 15:34 +0100, Borislav Petkov wrote:
> On Sun, Feb 24, 2013 at 12:42:55PM +0100, Peter Feuerer wrote:
> > Please test my last patch with the 4 trip points ;) - even if you
> > don't really like it, it is working great! - And to be honest, I still
> > prefer this solution!
> 
> Ok, I remember everything now - had to add some debug output to see what
> the stepwise governor hands us down.
> 
> Btw, Zhang, is there any way we can tell the upper layer to not
> poll trips and temps for this driver? I mean, ->get_trip_type and
> ->get_trip_temp get called every polling interval and the data it
> receives back each time is static and don't change so polling the same
> values each time for this driver doesn't make any sense.
> 
the reason we keep on calling it because the thermal zone trip point
info may be changed at runtime.

> Can we pass trip points and temperature levels upon registration time
> instead?
> 
no, but we can cache it in the thermal layer, and do update when
necessary.

> @Peter: I took your patch, removed one trip point and added comments so
> that we don't forget why we do what we do. Please take a look - it works
> fine here.
> 
> --
> From 1827ed71ff1b73a83d81d21f9dd167fe8e0d4198 Mon Sep 17 00:00:00 2001
> From: Peter Feuerer <peter@piie.net>
> Date: Sun, 24 Feb 2013 15:04:17 +0100
> Subject: [PATCH] acerhdf: Fix fan activation with new thermal governor
> 
> After recent thermal subsys rework, acerhdf couldn't cope with the
> stepwise governor since it had only one trip point and this didn't fit
> into the stepwise scheme.

why? I do not think the stepwise scheme will break it. If it happens, we
should fix stepwise governor instead.

>  Therefore, add two more trip points - an
> active one where we turn on the fan, and a critical one.
> 
I think you add a passive trip point and a critical one here.

> However, we still need to flatten out peaks of turning the fan on
> and off in acerhdf_set_cur_state because stepwise looks also at the
> direction the temperature is going and applies respective policy. This
> results in short bursts of interchanging on and off which are really
> annoying.
> 
> So, we keep the old logic where we turn on the fan only if we exceed
> 'fanon' temperature and leave it on until we go under 'fanoff'. Document
> this behavior while at it.
> 
has anybody checked if the patch at lkml.org/lkml/2012/12/30/47 fixes
the problem, without any other patch?

thanks,
rui
> Signed-off-by: Peter Feuerer <peter@piie.net>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> ---
>  drivers/platform/x86/acerhdf.c | 30 ++++++++++++++++++++++++++----
>  1 file changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/platform/x86/acerhdf.c b/drivers/platform/x86/acerhdf.c
> index f94467c05225..b06cdb099e6a 100644
> --- a/drivers/platform/x86/acerhdf.c
> +++ b/drivers/platform/x86/acerhdf.c
> @@ -400,7 +400,13 @@ static int acerhdf_get_trip_type(struct thermal_zone_device *thermal, int trip,
>  				 enum thermal_trip_type *type)
>  {
>  	if (trip == 0)
> +		*type = THERMAL_TRIP_PASSIVE;
> +	else if (trip == 1)
>  		*type = THERMAL_TRIP_ACTIVE;
> +	else if (trip == 2)
> +		*type = THERMAL_TRIP_CRITICAL;
> +	else
> +		WARN_ONCE(1, "%s: Funny trip point %d\n", KBUILD_MODNAME, trip);
>  
>  	return 0;
>  }
> @@ -409,7 +415,13 @@ static int acerhdf_get_trip_temp(struct thermal_zone_device *thermal, int trip,
>  				 unsigned long *temp)
>  {
>  	if (trip == 0)
> +		*temp = 0;
> +	else if (trip == 1)
>  		*temp = fanon;
> +	else if (trip == 2)
> +		*temp = ACERHDF_TEMP_CRIT;
> +	else
> +		WARN_ONCE(1, "%s: Funny trip point %d\n", KBUILD_MODNAME, trip);
>  
>  	return 0;
>  }
> @@ -459,7 +471,9 @@ static int acerhdf_get_cur_state(struct thermal_cooling_device *cdev,
>  	return 0;
>  }
>  
> -/* change current fan state - is overwritten when running in kernel mode */
> +/*
> + * Change current fan state - is overwritten when running in kernel mode
> + */
>  static int acerhdf_set_cur_state(struct thermal_cooling_device *cdev,
>  				 unsigned long state)
>  {
> @@ -480,15 +494,23 @@ static int acerhdf_set_cur_state(struct thermal_cooling_device *cdev,
>  		goto err_out;
>  	}
>  
> +	/*
> +	 * We need to flatten out the on-off peaks we get from the stepwise
> +	 * governor into the wider span between fanoff and fanon because
> +	 * otherwise we turn on/off the fan in short bursts, everytime the
> +	 * thermal zone decides to throttle and this is annoying.
> +	 */
>  	if (state == 0) {
>  		/* turn fan off only if below fanoff temperature */
>  		if ((cur_state == ACERHDF_FAN_AUTO) &&
> -		    (cur_temp < fanoff))
> +		    (cur_temp <= fanoff))
>  			acerhdf_change_fanstate(ACERHDF_FAN_OFF);
>  	} else {
> -		if (cur_state == ACERHDF_FAN_OFF)
> +		if ((cur_state == ACERHDF_FAN_OFF) &&
> +		    (cur_temp >= fanon))
>  			acerhdf_change_fanstate(ACERHDF_FAN_AUTO);
>  	}
> +
>  	return 0;
>  
>  err_out:
> @@ -661,7 +683,7 @@ static int acerhdf_register_thermal(void)
>  	if (IS_ERR(cl_dev))
>  		return -EINVAL;
>  
> -	thz_dev = thermal_zone_device_register("acerhdf", 1, 0, NULL,
> +	thz_dev = thermal_zone_device_register("acerhdf", 3, 0, NULL,
>  					      &acerhdf_dev_ops, NULL, 0,
>  					      (kernelmode) ? interval*1000 : 0);
>  	if (IS_ERR(thz_dev))
> -- 
> 1.8.1.3.535.ga923c31
> 
>