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Improve fan type detection for dell-smm to prevent kernel hang 

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Merge tag 'hwmon-for-linus-v4.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging

Pull hwmon fix from Guenter Roeck:
 "Improve fan type detection for dell-smm to prevent kernel hang"

* tag 'hwmon-for-linus-v4.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (dell-smm) Cache fan_type() calls and change fan detection
This commit is contained in:
Linus Torvalds 2016-06-24 18:36:15 -07:00
parent ed13fbbf87 5ce91714b0
commit 260eaba4ea
1 changed files with 20 additions and 5 deletions
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25
drivers/hwmon/dell-smm-hwmon.c
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@ -238,7 +238,7 @@ static int i8k_get_fan_speed(int fan)
/*
* Read the fan type.
*/
static int i8k_get_fan_type(int fan)
static int _i8k_get_fan_type(int fan)
{
struct smm_regs regs = { .eax = I8K_SMM_GET_FAN_TYPE, };
@ -249,6 +249,17 @@ static int i8k_get_fan_type(int fan)
return i8k_smm(&regs) ? : regs.eax & 0xff;
}
static int i8k_get_fan_type(int fan)
{
/* I8K_SMM_GET_FAN_TYPE SMM call is expensive, so cache values */
static int types[2] = { INT_MIN, INT_MIN };
if (types[fan] == INT_MIN)
types[fan] = _i8k_get_fan_type(fan);
return types[fan];
}
/*
* Read the fan nominal rpm for specific fan speed.
*/
@ -782,13 +793,17 @@ static int __init i8k_init_hwmon(void)
if (err >= 0)
i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP4;
/* First fan attributes, if fan type is OK */
err = i8k_get_fan_type(0);
/* First fan attributes, if fan status or type is OK */
err = i8k_get_fan_status(0);
if (err < 0)
err = i8k_get_fan_type(0);
if (err >= 0)
i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN1;
/* Second fan attributes, if fan type is OK */
err = i8k_get_fan_type(1);
/* Second fan attributes, if fan status or type is OK */
err = i8k_get_fan_status(1);
if (err < 0)
err = i8k_get_fan_type(1);
if (err >= 0)
i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN2;