hwmon: (coretemp) Do not return -EAGAIN for low temperatures

Some Intel CPUs do not set the 'valid' bit in IA32_THERM_STATUS if the
temperature is too low to be measured. This condition will not change until
the CPU is hot enough for its temperature to be measured. Returning an error
in such conditions is not very useful. Drop checking the valid bit and just
return the reported temperature instead.

Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 9 insertions, 8 deletions

diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index b2e59b3..bbb0b0d 100644
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -177,18 +177,19 @@ static ssize_t show_temp(struct device *dev,
 	/* Check whether the time interval has elapsed */
 	if (!tdata->valid || time_after(jiffies, tdata->last_updated + HZ)) {
 		rdmsr_on_cpu(tdata->cpu, tdata->status_reg, &eax, &edx);
-		tdata->valid = 0;
-		/* Check whether the data is valid */
-		if (eax & 0x80000000) {
-			tdata->temp = tdata->tjmax -
-					((eax >> 16) & 0x7f) * 1000;
-			tdata->valid = 1;
-		}
+		/*
+		 * Ignore the valid bit. In all observed cases the register
+		 * value is either low or zero if the valid bit is 0.
+		 * Return it instead of reporting an error which doesn't
+		 * really help at all.
+		 */
+		tdata->temp = tdata->tjmax - ((eax >> 16) & 0x7f) * 1000;
+		tdata->valid = 1;
 		tdata->last_updated = jiffies;
 	}
 
 	mutex_unlock(&tdata->update_lock);
-	return tdata->valid ? sprintf(buf, "%d\n", tdata->temp) : -EAGAIN;
+	return sprintf(buf, "%d\n", tdata->temp);
 }
 
 struct tjmax_pci {