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Commit 564132d9 authored by Guenter Roeck's avatar Guenter Roeck Committed by Greg Kroah-Hartman
Browse files

i8k: Rework error retries 



Instead of returning a previous value if the SMM code returns
an error when trying to read a temperature, retry once.
If that fails again, return -ENODATA. Also return -ENODATA if an
attempt is made to read the GPU temperature but the GPU is
currently turned off.

Drop the I8K_TEMPERATURE_BUG definition and handle the related bug
unconditionally.

Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Tested-by: default avatarPali Rohár <pali.rohar@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 83d514d7

drivers/char/i8k.c

+24 −23
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ 
 *

 * Hwmon integration:

 * Copyright (C) 2011  Jean Delvare <jdelvare@suse.de>

 * Copyright (C) 2013  Guenter Roeck <linux@roeck-us.net>

 * Copyright (C) 2013, 2014  Guenter Roeck <linux@roeck-us.net>

 *

 * 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
@@ -20,6 +20,7 @@ 


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt



#include <linux/delay.h>

#include <linux/module.h>

#include <linux/types.h>

#include <linux/init.h>
@@ -59,8 +60,6 @@ 
#define I8K_POWER_AC		0x05

#define I8K_POWER_BATTERY	0x01



#define I8K_TEMPERATURE_BUG	1



static DEFINE_MUTEX(i8k_mutex);

static char bios_version[4];

static struct device *i8k_hwmon_dev;
@@ -300,39 +299,41 @@ static int i8k_get_temp_type(int sensor) 
/*

 * Read the cpu temperature.

 */

static int i8k_get_temp(int sensor)

static int _i8k_get_temp(int sensor)

{

	struct smm_regs regs = { .eax = I8K_SMM_GET_TEMP, };

	int rc;

	int temp;

	struct smm_regs regs = {

		.eax = I8K_SMM_GET_TEMP,

		.ebx = sensor & 0xff,

	};



#ifdef I8K_TEMPERATURE_BUG

	static int prev[4] = { I8K_MAX_TEMP+1, I8K_MAX_TEMP+1, I8K_MAX_TEMP+1, I8K_MAX_TEMP+1 };

#endif

	regs.ebx = sensor & 0xff;

	rc = i8k_smm(&regs);

	if (rc < 0)

		return rc;

	return i8k_smm(&regs) ? : regs.eax & 0xff;

}



	temp = regs.eax & 0xff;

static int i8k_get_temp(int sensor)

{

	int temp = _i8k_get_temp(sensor);



#ifdef I8K_TEMPERATURE_BUG

	/*

	 * Sometimes the temperature sensor returns 0x99, which is out of range.

	 * In this case we return (once) the previous cached value. For example:

	 * In this case we retry (once) before returning an error.

	 # 1003655137 00000058 00005a4b

	 # 1003655138 00000099 00003a80 <--- 0x99 = 153 degrees

	 # 1003655139 00000054 00005c52

	 */

	if (temp > I8K_MAX_TEMP) {

		temp = prev[sensor];

		prev[sensor] = I8K_MAX_TEMP+1;

	} else {

		prev[sensor] = temp;

	if (temp == 0x99) {

		msleep(100);

		temp = _i8k_get_temp(sensor);

	}

	/*

	 * Return -ENODATA for all invalid temperatures.

	 *

	 * Known instances are the 0x99 value as seen above as well as

	 * 0xc1 (193), which may be returned when trying to read the GPU

	 * temperature if the system supports a GPU and it is currently

	 * turned off.

	 */

	if (temp > I8K_MAX_TEMP)

		return -ENODATA;

#endif



	return temp;

}