Message-ID: <20090503184617.GA3555@liondog.tnic>
Date:	Sun, 3 May 2009 20:46:17 +0200
From:	Borislav Petkov <petkovbb@...glemail.com>
To:	Peter Feuerer <peter@...e.net>
Cc:	LKML <linux-kernel@...r.kernel.org>, lenb@...nel.org,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Maxim Levitsky <maximlevitsky@...il.com>
Subject: Re: [PATCH] Acer Aspire One Fan Control

Hi,

this has definitely improved since the last one, thanks. See below for
comments.

On Sat, May 02, 2009 at 11:21:49PM +0200, Peter Feuerer wrote:
> Hi,
>
> here's a new patch, compiled and tested with current linus git state, 
> what's your opinion about it?
>
> cheers,
> --peter
>
>
> Acerhdf is a driver for Acer Aspire One netbooks. It allows to access
> the temperature sensor and to control the fan.
>
> Signed-off-by: Peter Feuerer <peter@...e.net>
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index ef03abe..0fc8f06 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -222,6 +222,13 @@ L:	linux-acenic@...site.dk
> S:	Maintained
> F:	drivers/net/acenic*
>
> +ACER ASPIRE ONE TEMPERATURE AND FAN DRIVER
> +P: Peter Feuerer
> +M: peter@...e.net
> +W: http://piie.net/?section=acerhdf
> +S: Maintained
> +F: drivers/platform/x86/acerhdf.c
> +
> ACER WMI LAPTOP EXTRAS
> P:	Carlos Corbacho
> M:	carlos@...angeworlds.co.uk
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 284ebac..c4fce42 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -34,6 +34,24 @@ config ACER_WMI
> 	  If you have an ACPI-WMI compatible Acer/ Wistron laptop, say Y or M
> 	  here.
>
> +config ACERHDF
> +	tristate "Acer Aspire One temperature and fan driver"
> +	depends on THERMAL && THERMAL_HWMON
> +	---help---
> +	  This is a driver for Acer Aspire One netbooks. It allows to access
> +	  the temperature sensor and to control the fan.
> +
> +	  The driver is started in "user-mode" where the Bios takes care about

							BIOS

> +	  controlling the fan, unless a userspace program controls it.
> +	  To let the module handle the fan, do:
> +	  echo kernel > /sys/class/thermal/thermal_zone0/mode
> +
> +	  For more information about this driver see
> +	  <http://piie.net/files/acerhdf_README.txt>
> +
> +	  If you have an Acer Aspire One netbook, say Y or M
> +	  here.
> +
> config ASUS_LAPTOP
> 	tristate "Asus Laptop Extras (EXPERIMENTAL)"
> 	depends on ACPI
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index e40c7bd..641b8bf 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -9,6 +9,7 @@ obj-$(CONFIG_COMPAL_LAPTOP)	+= compal-laptop.o
> obj-$(CONFIG_DELL_LAPTOP)	+= dell-laptop.o
> obj-$(CONFIG_DELL_WMI)		+= dell-wmi.o
> obj-$(CONFIG_ACER_WMI)		+= acer-wmi.o
> +obj-$(CONFIG_ACERHDF)		+= acerhdf.o
> obj-$(CONFIG_HP_WMI)		+= hp-wmi.o
> obj-$(CONFIG_TC1100_WMI)	+= tc1100-wmi.o
> obj-$(CONFIG_SONY_LAPTOP)	+= sony-laptop.o
> diff --git a/drivers/platform/x86/acerhdf.c b/drivers/platform/x86/acerhdf.c
> new file mode 100644
> index 0000000..9da4223
> --- /dev/null
> +++ b/drivers/platform/x86/acerhdf.c
> @@ -0,0 +1,501 @@
> +/*
> + * acerhdf - A kernelmodule which monitors the temperature
> + *           of the aspire one netbook, turns on/off the fan
> + *           as soon as the upper/lower threshold is reached.
> + *
> + * (C) 2009 - Peter Feuerer     peter (a) piie.net
> + *                              http://piie.net
> + *
> + *
> + *

too many newlines

> + * Inspired by and many thanks to:
> + *  o acerfand   - Rachel Greenham
> + *  o acer_ec.pl - Michael Kurz     michi.kurz (at) googlemail.com
> + *               - Petr Tomasek     tomasek (#) etf,cuni,cz
> + *               - Carlos Corbacho  cathectic (at) gmail.com
> + *
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; either version 2 of the License, or
> + *  (at your option) any later version.
> + *
> + *  This program is distributed in the hope that it will be useful,
> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + *  GNU General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License
> + *  along with this program; if not, write to the Free Software
> + *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/fs.h>
> +#include <linux/dmi.h>
> +#include <acpi/acpi_drivers.h>
> +#include <linux/sched.h>
> +#include <linux/thermal.h>
> +#include <linux/platform_device.h>
> +
> +/* if you want the module to be started in kernelmode,
> + * uncomment following line */
> +/* #define START_IN_KERNEL_MODE */
> +
> +#define VERSION "0.5.1"
> +/* Referring the atom spec, are 99 degree Celsius ok. So critical
> + * temperature is 89 degree Celsius to prevent hardware damage */

Which spec exactly, URL? The Atom N270 datasheet
(http://download.intel.com/design/processor/datashts/320032.pdf)
says the CPU's optimal operating limits wrt to junction temperature
as measured by the on-die thermal monitor is 0 <= Tj <= 90. Is this
the temperature you mean? How do you come up with the value of 89°C
critical temp?

> +#define ACERHDF_TEMP_CRIT 89
> +#define ACERHDF_FAN_AUTO 1
> +#define ACERHDF_FAN_OFF 0
> +/* No matter what value the user puts into the fanon variable, turn on the fan
> + * at 80 degree Celsius to prevent hardware damage */
> +#define ACERHDF_MAX_FANON 80
> +#define ACERHDF_ERROR -0xffff
> +#define K_NOTICE KERN_NOTICE "acerhdf: "
> +#define K_ERR KERN_ERR "acerhdf: "

no, this way is ugly and causes confusion. Define your own macros instead:

	#define acerhdf_printk(loglevel, fmt, args)    \
		printk(loglevel "acerhdf: " fmt, args);

	#define acerhdf_notice(fmt, args...)	\
		acerhdf_printk(KERN_NOTICE, fmt, ## args);

	#define acerhdf_err(fmt, args...)	\
		acerhdf_printk(KERN_ERR, fmt, ## args);

and then do

	acerhdf_notice("interval changed to: %d\n", interval);

for example.

> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Peter Feuerer");
> +MODULE_DESCRIPTION("Aspire One temperature and fan driver");
> +MODULE_ALIAS("dmi:*:*Acer*:*:");
> +MODULE_ALIAS("dmi:*:*Gateway*:*:");
> +MODULE_ALIAS("dmi:*:*Packard Bell*:*:");
> +
> +/* global variables */
> +

unneeded comment

> +#ifdef START_IN_KERNEL_MODE
> +static int kernelmode = 1;
> +#else /* START_IN_KERNEL_MODE */
> +static int kernelmode;
> +#endif /* START_IN_KERNEL_MODE */
> +
> +static int interval = 10;
> +static int fanon = 67;
> +static int fanoff = 62;
> +static int verbose;
> +static int fanstate = 1;

static int fanstate = ACERHDF_FAN_AUTO;

> +static int disable_kernelmode;
> +static int bios_version = -1;
> +static char force_bios[16];
> +static int prev_interval;
> +struct thermal_zone_device *acerhdf_thz_dev;
> +struct thermal_cooling_device *acerhdf_cool_dev;
> +
> +/* module parameters */

unneeded comment

> +module_param(kernelmode, int, 0);
> +MODULE_PARM_DESC(kernelmode, "Kernel mode on / off");
> +module_param(interval, int, 0600);
> +MODULE_PARM_DESC(interval, "Polling interval of temperature check");
> +module_param(fanon, int, 0600);
> +MODULE_PARM_DESC(fanon, "Turn the fan on above this temperature");
> +module_param(fanoff, int, 0600);
> +MODULE_PARM_DESC(fanoff, "Turn the fan off below this temperature");
> +module_param(verbose, int, 0600);
> +MODULE_PARM_DESC(verbose, "Enable verbose dmesg outputs");
> +module_param_string(force_bios, force_bios, 16, 0);
> +MODULE_PARM_DESC(force_bios, "Force bios version and omit bios check");
> +
> +/* bios settings */
> +/**********************************************************************/
> +struct bios_settings_t {
> +	const char *vendor;
> +	const char *version;
> +	unsigned char fanreg;
> +	unsigned char tempreg;
> +	unsigned char cmd_off;
> +	unsigned char cmd_auto;
> +};
> +
> +/* some bios versions have different commands and
> + * maybe also different register addresses */
> +static const struct bios_settings_t bios_settings[] = {
> +	{"Acer", "v0.3109", 0x55, 0x58, 0x1f, 0x00},
> +	{"Acer", "v0.3114", 0x55, 0x58, 0x1f, 0x00},
> +	{"Acer", "v0.3301", 0x55, 0x58, 0xaf, 0x00},
> +	{"Acer", "v0.3304", 0x55, 0x58, 0xaf, 0x00},
> +	{"Acer", "v0.3305", 0x55, 0x58, 0xaf, 0x00},
> +	{"Acer", "v0.3308", 0x55, 0x58, 0x21, 0x00},
> +	{"Acer", "v0.3309", 0x55, 0x58, 0x21, 0x00},
> +	{"Gateway", "v0.3103", 0x55, 0x58, 0x21, 0x00},
> +	{"Packard Bell", "v0.3105", 0x55, 0x58, 0x21, 0x00},
> +	{"", 0, 0, 0, 0, 0}
> +};
> +
> +
> +/* acer ec functions */
> +/**********************************************************************/
> +/* return temperature */
> +static int acerhdf_get_temp(void)
> +{
> +	u8 temp;
> +	/* read temperature */
> +	if (!ec_read(bios_settings[bios_version].tempreg, &temp)) {
> +		if (verbose)
> +			printk(K_NOTICE "temp %d\n", temp);
> +		return temp;
> +	}
> +	return ACERHDF_ERROR;
> +}
> +
> +/* return state of the fan */
> +static int acerhdf_get_fanstate(void)
> +{
> +	u8 fan;
> +	if (!ec_read(bios_settings[bios_version].fanreg, &fan))
> +		return (fan == bios_settings[bios_version].cmd_off) ?
> +			ACERHDF_FAN_OFF : ACERHDF_FAN_AUTO;
> +
> +	return ACERHDF_ERROR;
> +}
> +
> +/* switch on/off the fan */
> +static void acerhdf_change_fanstate(int state)
> +{
> +	unsigned char cmd;

newline here would be better

> +	if (verbose)
> +		printk(K_NOTICE "fan %s\n", (state) ? "ON" : "OFF");
> +
> +	cmd = (state) ? bios_settings[bios_version].cmd_auto :
> +			bios_settings[bios_version].cmd_off;
> +
> +	ec_write(bios_settings[bios_version].fanreg, cmd);
> +
> +	fanstate = (state) ? ACERHDF_FAN_AUTO : ACERHDF_FAN_OFF;
> +}

but you still assume that the ON is 1 and OFF is 0 and are not using the
constants you've defined above. How about the following:


	if (state == ACERHDF_FAN_AUTO)
		cmd = bios_settings[bios_version].cmd_auto;
	else
		cmd = bios_settings[bios_version].cmd_off;

	ec_write(bios_settings[bios_version].fanreg, cmd);

	fanstate = state;


which is much more readable, IMHO.

> +
> +/* helpers */
> +/**********************************************************************/
> +/* check if parameters have changed */
> +static void acerhdf_check_param(struct thermal_zone_device *thermal)
> +{
> +	if (fanon > ACERHDF_MAX_FANON) {
> +		printk(K_ERR "fanon temperature too high, set to %d\n",
> +				ACERHDF_MAX_FANON);
> +		fanon = ACERHDF_MAX_FANON;
> +	}
> +	if (kernelmode && prev_interval != interval) {

how about a max interval also, just in case, similar to the MAX_FANON thingy
above.

> +		if (verbose)
> +			printk(K_NOTICE "interval changed to: %d\n",
> +					interval);
> +		thermal->polling_delay = interval*1000;
> +		prev_interval = interval;
> +	}
> +}
> +
> +/* thermal zone callback functions */
> +/**********************************************************************/
> +/* return temperature */
> +static int get_ec_temp(struct thermal_zone_device *thermal, unsigned long *t)
> +{
> +	int temp;
> +
> +	/* check if parameters have changed */
> +	acerhdf_check_param(thermal);
> +
> +	/* return temperature */
> +	temp = acerhdf_get_temp();
> +	if (temp == ACERHDF_ERROR)
> +		return -EINVAL;
> +
> +	*t = temp;
> +	return 0;
> +}
> +
> +/* bind the cooling device to the thermal zone */
> +static int bind(struct thermal_zone_device *thermal,
> +		struct thermal_cooling_device *cdev)
> +{
> +	/* if the cooling device is the one from acerhdf bind it */
> +	if (cdev == acerhdf_cool_dev) {
> +		if (thermal_zone_bind_cooling_device(thermal, 0, cdev)) {
> +			printk(K_ERR "error binding cooling dev\n");
> +			return -EINVAL;
> +		}
> +	}
> +	return 0;
> +}
> +
> +/* unbind cooling device from thermal zone */
> +static int unbind(struct thermal_zone_device *thermal,
> +		struct thermal_cooling_device *cdev)
> +{
> +	if (cdev == acerhdf_cool_dev) {
> +		if (thermal_zone_unbind_cooling_device(thermal, 0, cdev)) {
> +			printk(K_ERR "acerhdf: error unbinding cooling dev\n");
> +			return -EINVAL;
> +		}
> +	}
> +	return 0;
> +}
> +
> +/*  current operation mode - kernel / user */
> +static int get_mode(struct thermal_zone_device *thermal,
> +		enum thermal_device_mode *mode)
> +{
> +	if (verbose)
> +		printk(K_NOTICE "kernelmode %d\n", kernelmode);
> +
> +	*mode = (kernelmode) ? THERMAL_DEVICE_ENABLED :
> +		THERMAL_DEVICE_DISABLED;
> +
> +	return 0;
> +}
> +
> +/* set operation mode;
> + * kernel: the thermal layer of the kernel takes care about
> + *         the temperature and the fan.
> + * user: the BIOS takes control of the fan until a userspace
> + *       tool does.
> + */
> +static int set_mode(struct thermal_zone_device *thermal,
> +		enum thermal_device_mode mode)
> +{
> +	if (mode == THERMAL_DEVICE_DISABLED) {
> +		if (verbose)
> +			printk(K_NOTICE "kernelmode OFF\n");

as before, those shouldn't be verbose - they're important enough to
appear in syslog.

> +		thermal->polling_delay = 0;
> +		thermal_zone_device_update(thermal);
> +		acerhdf_change_fanstate(ACERHDF_FAN_AUTO);
> +
> +		/* let the thermal layer disable kernelmode. This ensures that
> +		 * the thermal layer doesn't switch off the fan again */
> +		disable_kernelmode = 1;
> +	} else {
> +		if (verbose)
> +			printk(K_NOTICE "kernelmode ON\n");

ditto.

> +		thermal->polling_delay = interval*1000;
> +		thermal_zone_device_update(thermal);
> +		kernelmode = 1;
> +	}
> +	return 0;
> +}
> +
> +/* get the type of the trip point */
> +static int get_trip_type(struct thermal_zone_device *thermal,
> +		int trip, enum thermal_trip_type *type)
> +{
> +	if (trip == 0)
> +		*type = THERMAL_TRIP_ACTIVE;
> +	return 0;
> +}
> +
> +/* get the temperature at which the trip point gets active */
> +static int get_trip_temp(struct thermal_zone_device *thermal,
> +		int trip, unsigned long *temp)
> +{
> +	if (trip == 0)
> +		*temp = fanon;
> +	return 0;
> +}
> +
> +static int get_crit_temp(struct thermal_zone_device *thermal,
> +		unsigned long *temperature)
> +{
> +	*temperature = ACERHDF_TEMP_CRIT;
> +	return 0;
> +}
> +
> +/* bind callback functions to thermalzone */
> +struct thermal_zone_device_ops acerhdf_device_ops = {
> +	.bind = bind,
> +	.unbind = unbind,
> +	.get_temp = get_ec_temp,
> +	.get_mode = get_mode,
> +	.set_mode = set_mode,
> +	.get_trip_type = get_trip_type,
> +	.get_trip_temp = get_trip_temp,
> +	.get_crit_temp = get_crit_temp,

how about prefixes to all those functions too? This way it is confusing
and the function names are too generic, possibly leading to conflicts
later.

> +};
> +
> +
> +/* cooling device callback functions */
> +/**********************************************************************/
> +/* get maximal fan cooling state */
> +static int get_max_state(struct thermal_cooling_device *cdev,
> +		unsigned long *state)
> +{
> +	*state = 1;
> +	return 0;
> +}
> +
> +/* get current fan state */
> +static int get_cur_state(struct thermal_cooling_device *cdev,
> +		unsigned long *state)
> +{
> +	unsigned long st = acerhdf_get_fanstate();
> +
> +	if (st == ACERHDF_ERROR)
> +		return -EINVAL;
> +
> +	*state = st;
> +	return 0;
> +}
> +
> +/* change current fan state - is overwritten when running in kernel mode */
> +static int set_cur_state(struct thermal_cooling_device *cdev,
> +		unsigned long state)
> +{
> +	int old_state;
> +
> +	/* let the thermal layer disable kernelmode. This ensures that
> +	 * the thermal layer doesn't switch off the fan again */
> +	if (disable_kernelmode) {
> +		acerhdf_change_fanstate(ACERHDF_FAN_AUTO);
> +		disable_kernelmode = 0;
> +		kernelmode = 0;
> +		return 0;
> +	}
> +
> +	if (!kernelmode) {
> +		acerhdf_change_fanstate(state);
> +		return 0;
> +	}

why are we changing the fan state if kernelmode is off? If I'm not
mistaken, the BIOS should be controlling the fan here.

> +
> +	old_state = acerhdf_get_fanstate();
> +
> +	/* if reading the fan's state returns unexpected value, there's a
> +	 * problem with the ec register. -> let the BIOS take control of
> +	 * the fan to prevent hardware damage */
> +	if (old_state != fanstate) {

you should be checking 

	old_state == ACERHDF_ERROR

here instead.

> +		printk(K_ERR "failed reading fan state, "
> +				"disabling kernelmode.\n");
> +
> +		if (verbose)
> +			printk(K_ERR "read state: %d expected state: %d\n",
> +					old_state, fanstate);
> +
> +		acerhdf_change_fanstate(ACERHDF_FAN_AUTO);
> +		disable_kernelmode = 1;
> +	}
> +
> +	if (state && !old_state)
> +		acerhdf_change_fanstate(ACERHDF_FAN_AUTO);
> +
> +	if (!state && old_state && (acerhdf_get_temp() < fanoff))
> +		acerhdf_change_fanstate(ACERHDF_FAN_OFF);

You're assuming here again that state AUTO is 1 (true value) and state
OFF os 0 (false value) which makes the code hard to read and understand.
The thermal_sys.c code is also broken because it is using naked values
too.

How about:

if (old_state == ACERHDF_FAN_AUTO) {
	/*
	 * turn fan off only if below fanoff temperature
	 */
	if ((state == ACERHDF_FAN_OFF) && (acerhdf_get_temp() < fanoff))
		acerhdf_change_fanstate(ACERHDF_FAN_OFF);
} else {
	if (state == ACERHDF_FAN_AUTO)
		acerhdf_change_fanstate(ACERHDF_FAN_AUTO);
}


This way you can completely omit the 'fanstate' variable.

> +	return 0;
> +}
> +
> +/* bind fan callbacks to fan device */
> +struct thermal_cooling_device_ops acerhdf_cooling_ops = {
> +	.get_max_state = get_max_state,
> +	.get_cur_state = get_cur_state,
> +	.set_cur_state = set_cur_state,
> +};
> +
> +/* kernel module init / exit functions */
> +/**********************************************************************/
> +/* initialize the module */
> +static int __init acerhdf_init(void)
> +{
> +	char const *vendor;
> +	char const *version;
> +	char const *release;
> +	char const *product;
> +	int i;
> +	int ret_val = 0;
> +
> +
> +	/* get bios data */
> +	vendor = dmi_get_system_info(DMI_SYS_VENDOR);
> +	version = dmi_get_system_info(DMI_BIOS_VERSION);
> +	release = dmi_get_system_info(DMI_BIOS_DATE);
> +	product = dmi_get_system_info(DMI_PRODUCT_NAME);
> +
> +
> +	/* print out bios data */
> +	printk(K_NOTICE "version: %s compilation date: %s %s\n",
> +			VERSION, __DATE__, __TIME__);

no need for __DATE__ and __TIME__.

> +	printk(K_NOTICE "BIOS vendor:%s versoin:%s\n", vendor, version);

					version

> +	if (verbose)
> +		printk(K_NOTICE "BIOS release:%s product:%s\n",
> +				release, product);
> +
> +	if (!force_bios[0]) {
> +		/* check if product is a AO - Aspire One */
> +		if (strncmp(product, "AO", 2)) {
> +			printk(K_ERR "no Aspire One hardware found\n");
> +			ret_val = -ENODEV;
> +			goto EXIT;
> +		}
> +	} else {
> +		printk(K_NOTICE "acerhdf: bios version: %s forced\n", version);

					  BIOS

> +		version = force_bios;
> +		kernelmode = 0;
> +	}
> +
> +	/* if started in user mode, prevent the kernel from switching
> +	 * off the fan */
> +	if (!kernelmode) {
> +		disable_kernelmode = 1;
> +		printk(K_NOTICE "kernelmode OFF, to enable:\n");
> +		printk(K_NOTICE "echo -n \"enabled\" > "
> +			"/sys/class/thermal/thermal_zone0/mode\n");
> +		printk(K_NOTICE "http://piie.net/files/acerhdf_README.txt\n");
> +	}
> +
> +
> +	/* search bios and bios vendor in bios settings table */
> +	for (i = 0; bios_settings[i].version[0]; ++i) {
> +		if (!strcmp(bios_settings[i].vendor, vendor) &&
> +				!strcmp(bios_settings[i].version, version)) {
> +			bios_version = i;
> +			break;
> +		}
> +	}
> +	if (bios_version == -1) {
> +		printk(K_ERR "cannot find bios version\n");
> +		ret_val = -ENODEV;
> +		goto EXIT;
> +	}
> +
> +	acerhdf_cool_dev = thermal_cooling_device_register("acerhdf-fan", NULL,
> +			&acerhdf_cooling_ops);
> +	if (IS_ERR(acerhdf_cool_dev)) {
> +		ret_val = -ENODEV;
> +		goto EXIT;
> +	}
> +
> +	acerhdf_thz_dev = thermal_zone_device_register("acerhdf", 1,
> +			NULL, &acerhdf_device_ops, 0, 0, 0,
> +			(kernelmode) ? interval*1000 : 0);
> +	if (IS_ERR(acerhdf_thz_dev)) {
> +		ret_val = -ENODEV;
> +		goto EXIT_COOL_UNREG;
> +	}
> +
> +	goto EXIT;
> +
> +EXIT_COOL_UNREG:
> +	if (acerhdf_cool_dev) {
> +		thermal_cooling_device_unregister(acerhdf_cool_dev);
> +		acerhdf_cool_dev = NULL;
> +	}
> +
> +EXIT:
> +	return ret_val;
> +}
> +
> +/* exit the module */
> +static void __exit acerhdf_exit(void)
> +{
> +	acerhdf_change_fanstate(ACERHDF_FAN_AUTO);
> +
> +	if (acerhdf_cool_dev) {
> +		thermal_cooling_device_unregister(acerhdf_cool_dev);
> +		acerhdf_cool_dev = NULL;
> +	}
> +
> +	if (acerhdf_thz_dev) {
> +		thermal_zone_device_unregister(acerhdf_thz_dev);
> +		acerhdf_thz_dev = NULL;
> +	}
> +}
> +
> +/* what are the module init/exit functions */
> +module_init(acerhdf_init);
> +module_exit(acerhdf_exit);

-- 
Regards/Gruss,
    Boris.
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