[PATCH] i8k: Fix temperature bug handling in i8k_get_temp()

From: Pali RohÃr
Date: Tue Nov 18 2014 - 09:58:56 EST


Static array prev[] was incorrectly initialized. It should be initialized to
some "invalid" temperature value (above I8K_MAX_TEMP).

Next, function should store "invalid" value to prev[] (above I8K_MAX_TEMP),
not valid (= I8K_MAX_TEMP) because whole temperature bug handling will not
work.

And last part, to not break existing detection of temperature sensors, register
them also if i8k report too high temperature (above I8K_MAX_TEMP). This is
needed because some sensors are sometimes turned off (e.g sensor on GPU which
can be turned off/on) and in this case SMM report too high value.

To prevent reporting "invalid" values to userspace, return -EINVAL. In this case
sensors which are currently turned off (e.g optimus/powerexpress/enduro gpu)
are reported as "N/A" by lm-sensors package.

Signed-off-by: Pali RohÃr <pali.rohar@xxxxxxxxx>
---
drivers/char/i8k.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c
index 7272b08..e34a019 100644
--- a/drivers/char/i8k.c
+++ b/drivers/char/i8k.c
@@ -298,7 +298,7 @@ static int i8k_get_temp(int sensor)
int temp;

#ifdef I8K_TEMPERATURE_BUG
- static int prev[4];
+ 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);
@@ -317,10 +317,12 @@ static int i8k_get_temp(int sensor)
*/
if (temp > I8K_MAX_TEMP) {
temp = prev[sensor];
- prev[sensor] = I8K_MAX_TEMP;
+ prev[sensor] = I8K_MAX_TEMP+1;
} else {
prev[sensor] = temp;
}
+ if (temp > I8K_MAX_TEMP)
+ return -ERANGE;
#endif

return temp;
@@ -499,6 +501,8 @@ static ssize_t i8k_hwmon_show_temp(struct device *dev,
int temp;

temp = i8k_get_temp(index);
+ if (temp == -ERANGE)
+ return -EINVAL;
if (temp < 0)
return temp;
return sprintf(buf, "%d\n", temp * 1000);
@@ -610,17 +614,17 @@ static int __init i8k_init_hwmon(void)

/* CPU temperature attributes, if temperature reading is OK */
err = i8k_get_temp(0);
- if (err >= 0)
+ if (err >= 0 || err == -ERANGE)
i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP1;
/* check for additional temperature sensors */
err = i8k_get_temp(1);
- if (err >= 0)
+ if (err >= 0 || err == -ERANGE)
i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP2;
err = i8k_get_temp(2);
- if (err >= 0)
+ if (err >= 0 || err == -ERANGE)
i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP3;
err = i8k_get_temp(3);
- if (err >= 0)
+ if (err >= 0 || err == -ERANGE)
i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP4;

/* Left fan attributes, if left fan is present */
--
1.7.9.5

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