Re: [RESEND PATCH v5 3/5] acerhdf: Use bang-bang thermal governor

[Darren Hart <dvhart@infradead.org>]

On Fri, Nov 28, 2014 at 03:20:50PM +0100, Peter Feuerer wrote:
> acerhdf has been doing an on-off fan control using hysteresis by
> post-manipulating the outcome of thermal subsystem trip point handling.
> This patch enables acerhdf to use the bang-bang governor, which is
> intended for on-off controlled fans.
> 
> Cc: platform-driver-x86@vger.kernel.org
> Cc: Darren Hart <dvhart@infradead.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> CC: Zhang Rui <rui.zhang@intel.com>
> Cc: Andreas Mohr <andi@lisas.de>
> Cc: Javi Merino <javi.merino@arm.com>
> Acked-and-tested-by: Borislav Petkov <bp@suse.de>
> Signed-off-by: Peter Feuerer <peter@piie.net>
> ---
>  drivers/platform/x86/Kconfig   |  3 ++-
>  drivers/platform/x86/acerhdf.c | 36 +++++++++++++++++++++++++++++++-----
>  2 files changed, 33 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index a2eabe6..c173266 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -38,7 +38,8 @@ config ACER_WMI
>  
>  config ACERHDF
>  	tristate "Acer Aspire One temperature and fan driver"
> -	depends on THERMAL && ACPI
> +	select THERMAL_GOV_BANG_BANG

So we use select sparingly as it does implicit things.

I checked the THERMAL_GOV_BANG_BANG Kconfig entry, and the help says acerhdf
already depends on it (which it doesn't appear to). Any particular reason to add
select here instead of adding it as a depends.

Why did you drop THERMAL?

> +	depends on ACPI
>  	---help---
>  	  This is a driver for Acer Aspire One netbooks. It allows to access
>  	  the temperature sensor and to control the fan.
> diff --git a/drivers/platform/x86/acerhdf.c b/drivers/platform/x86/acerhdf.c
> index f30767f..7fe7dbf 100644
> --- a/drivers/platform/x86/acerhdf.c
> +++ b/drivers/platform/x86/acerhdf.c
> @@ -50,7 +50,7 @@
>   */
>  #undef START_IN_KERNEL_MODE
>  
> -#define DRV_VER "0.5.30"
> +#define DRV_VER "0.7.0"
>  
>  /*
>   * According to the Atom N270 datasheet,
> @@ -258,6 +258,14 @@ static const struct bios_settings_t bios_tbl[] = {
>  
>  static const struct bios_settings_t *bios_cfg __read_mostly;
>  
> +/*
> + * this struct is used to instruct thermal layer to use bang_bang instead of
> + * default governor for acerhdf

Please use sentence punctuation, particularly for block comments.

/*
 * This struct...
 * default ... for acerhdf.
 */

> + */
> +static struct thermal_zone_params acerhdf_zone_params = {
> +	.governor_name = "bang_bang",
> +};
> +
>  static int acerhdf_get_temp(int *temp)
>  {
>  	u8 read_temp;
> @@ -439,6 +447,17 @@ static int acerhdf_get_trip_type(struct thermal_zone_device *thermal, int trip,
>  	return 0;
>  }
>  
> +static int acerhdf_get_trip_hyst(struct thermal_zone_device *thermal, int trip,
> +				 unsigned long *temp)
> +{
> +	if (trip != 0)
> +		return -EINVAL;
> +
> +	*temp = fanon - fanoff;
> +
> +	return 0;
> +}
> +
>  static int acerhdf_get_trip_temp(struct thermal_zone_device *thermal, int trip,
>  				 unsigned long *temp)
>  {
> @@ -463,6 +482,7 @@ static struct thermal_zone_device_ops acerhdf_dev_ops = {
>  	.get_mode = acerhdf_get_mode,
>  	.set_mode = acerhdf_set_mode,
>  	.get_trip_type = acerhdf_get_trip_type,
> +	.get_trip_hyst = acerhdf_get_trip_hyst,
>  	.get_trip_temp = acerhdf_get_trip_temp,
>  	.get_crit_temp = acerhdf_get_crit_temp,
>  };
> @@ -515,9 +535,7 @@ static int acerhdf_set_cur_state(struct thermal_cooling_device *cdev,
>  	}
>  
>  	if (state == 0) {
> -		/* turn fan off only if below fanoff temperature */
> -		if ((cur_state == ACERHDF_FAN_AUTO) &&
> -		    (cur_temp < fanoff))
> +		if (cur_state == ACERHDF_FAN_AUTO)
>  			acerhdf_change_fanstate(ACERHDF_FAN_OFF);
>  	} else {
>  		if (cur_state == ACERHDF_FAN_OFF)
> @@ -696,11 +714,19 @@ static int acerhdf_register_thermal(void)
>  		return -EINVAL;
>  
>  	thz_dev = thermal_zone_device_register("acerhdf", 1, 0, NULL,
> -					      &acerhdf_dev_ops, NULL, 0,
> +					      &acerhdf_dev_ops,
> +					      &acerhdf_zone_params, 0,
>  					      (kernelmode) ? interval*1000 : 0);
>  	if (IS_ERR(thz_dev))
>  		return -EINVAL;
>  
> +	if (strcmp(thz_dev->governor->name,
> +				acerhdf_zone_params.governor_name)) {
> +		pr_err("Didn't get thermal governor %s, perhaps not compiled into thermal subsystem.\n",
> +				acerhdf_zone_params.governor_name);

We've ensured it has to be compiled in, so that really can't be it. Right?

> +		return -EINVAL;
> +	}
> +
>  	return 0;
>  }
>  
> -- 
> 2.1.3
> 
> 

-- 
Darren Hart
Intel Open Source Technology Center