Fix Linux to conform to 11.3.18 of the ACPI spec 3.0. In the absence of
a _TZP method, we should be polling at a default frequency. While it can
be argued that "0" is a default frequency, I don't think that's what the
spec authors had in mind.
Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
---
Arguably this should be implemented in such a way that the polling rate
increases as the temperature rises and drops if the trend is downwards.
That would give higher resolution when we're heading towards a trip
point, without any significant increase in power consumption since
increased temperatures imply that the CPU is probably not idle.
diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
index 504385b..93cb3e8 100644
--- a/drivers/acpi/thermal.c
+++ b/drivers/acpi/thermal.c
@@ -846,10 +846,11 @@ static void acpi_thermal_check(void *data)
* Calculate Sleep Time
* --------------------
* If we're in the passive state, use _TSP's value. Otherwise
- * use the default polling frequency (e.g. _TZP). If no polling
- * frequency is specified then we'll wait forever (at least until
- * a thermal event occurs). Note that _TSP and _TZD values are
- * given in 1/10th seconds (we must covert to milliseconds).
+ * use the default polling frequency (e.g. _TZP). If no
+ * polling frequency is specified then we'll wait 10 seconds
+ * (or until a thermal event occurs). Note that _TSP and _TZD
+ * values are given in 1/10th seconds (we must covert to
+ * milliseconds).
*/
if (tz->state.passive) {
sleep_time = tz->trips.passive.tsp * 100;
@@ -1575,8 +1576,9 @@ static int acpi_thermal_get_info(struct acpi_thermal *tz)
/* Get default polling frequency [_TZP] (optional) */
if (tzp)
tz->polling_frequency = tzp;
- else
- acpi_thermal_get_polling_frequency(tz);
+ else if (acpi_thermal_get_polling_frequency(tz) == -ENODEV)
+ /* If no _TZP, default to polling every 10 seconds */
+ tz->polling_frequency = 100;
return 0;
}
--
Matthew Garrett | mjg59@xxxxxxxxxxxxx
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