Commit c52a7419 authored by Len Brown's avatar Len Brown
Browse files

ACPI: thermal: create "thermal.crt=C" bootparam 

Some hardware will malfunction at a temperature below
the BIOS provided critical shutdown threshold.

This hook allows moving the critical trip points down
to a temperature which provokes a graceful shutdown
before the hardware malfunction.

http://bugzilla.kernel.org/show_bug.cgi?id=8884



WARNING: A trip-point override will not get noticed
until the system delivers a temperature change event,
or unless thermal zone polling is enabled.
eg. "thermal.tzp=10"

Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 3c1d36da

Documentation/kernel-parameters.txt

+4 −0
Original line number Diff line number Diff line
@@ -1826,6 +1826,10 @@ and is between 256 and 4096 characters. It is defined in the file 
			-1: disable all active trip points in all thermal zones

			<degrees C>: override all lowest active trip points



	thermal.crt=	[HW,ACPI]

			-1: disable all critical trip points in all thermal zones

			<degrees C>: lower all critical trip points



	thermal.nocrt=	[HW,ACPI]

			Set to disable actions on ACPI thermal zone

			critical and hot trip points.

drivers/acpi/thermal.c

+18 −0
Original line number Diff line number Diff line
@@ -79,6 +79,10 @@ static int act; 
module_param(act, int, 0644);

MODULE_PARM_DESC(act, "Disable or override all lowest active trip points.");



static int crt;

module_param(crt, int, 0644);

MODULE_PARM_DESC(crt, "Disable or lower all critical trip points.");



static int tzp;

module_param(tzp, int, 0444);

MODULE_PARM_DESC(tzp, "Thermal zone polling frequency, in 1/10 seconds.");
@@ -340,6 +344,20 @@ static int acpi_thermal_get_trip_points(struct acpi_thermal *tz) 
				  tz->trips.critical.temperature));

	}



	if (tz->trips.critical.flags.valid == 1) {

		if (crt == -1) {

			tz->trips.critical.flags.valid = 0;

		} else if (crt > 0) {

			unsigned long crt_k = CELSIUS_TO_KELVIN(crt);



			/*

			 * Allow override to lower critical threshold

			 */

			if (crt_k < tz->trips.critical.temperature)

				tz->trips.critical.temperature = crt_k;

		}

	}



	/* Critical Sleep (optional) */



	status =

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