thermal: Get rid of CONFIG_THERMAL_WRITABLE_TRIPS

The only difference made by CONFIG_THERMAL_WRITABLE_TRIPS is whether or
not the writable trips mask passed during thermal zone registration
will take any effect, but whoever passes a non-zero writable trips mask
to thermal_zone_device_register_with_trips() can be forgiven thinking
that it will always work.

Moreover, some thermal drivers expect user space to set trip temperature
values, so they select CONFIG_THERMAL_WRITABLE_TRIPS, possibly overriding
a manual choice to unset it and going against the design purportedly
allowing system integrators to decide on the writability of trip points
for the given kernel build.  It is also set in one platform's defconfig.

Forthermore, CONFIG_THERMAL_WRITABLE_TRIPS only affects trip temperature,
because trip hysteresis is writable as long as the thermal zone provides
a callback to update it, regardless of the CONFIG_THERMAL_WRITABLE_TRIPS
value.

The above means that the symbol in question is used inconsistently and
its purpose is at least moot, so remove it and always take the writable
trip mask passed to thermal_zone_device_register_with_trips() into
account.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Author: rafaeljw

arch/arm/configs/imx_v6_v7_defconfig

@@ -228,7 +228,6 @@ CONFIG_SENSORS_IIO_HWMON=y
 CONFIG_SENSORS_PWM_FAN=y
 CONFIG_SENSORS_SY7636A=y
 CONFIG_THERMAL_STATISTICS=y
-CONFIG_THERMAL_WRITABLE_TRIPS=y
 CONFIG_CPU_THERMAL=y
 CONFIG_IMX_THERMAL=y
 CONFIG_WATCHDOG=y

drivers/thermal/Kconfig

@@ -83,17 +83,6 @@ config THERMAL_OF
 	  Say 'Y' here if you need to build thermal infrastructure
 	  based on device tree.
 
-config THERMAL_WRITABLE_TRIPS
-	bool "Enable writable trip points"
-	help
-	  This option allows the system integrator to choose whether
-	  trip temperatures can be changed from userspace. The
-	  writable trips need to be specified when setting up the
-	  thermal zone but the choice here takes precedence.
-
-	  Say 'Y' here if you would like to allow userspace tools to
-	  change trip temperatures.
-
 choice
 	prompt "Default Thermal governor"
 	default THERMAL_DEFAULT_GOV_STEP_WISE

drivers/thermal/intel/Kconfig

@@ -23,7 +23,6 @@ config X86_PKG_TEMP_THERMAL
 	tristate "X86 package temperature thermal driver"
 	depends on X86_THERMAL_VECTOR
 	select THERMAL_GOV_USER_SPACE
-	select THERMAL_WRITABLE_TRIPS
 	select INTEL_TCC
 	default m
 	help
@@ -47,7 +46,6 @@ config INTEL_SOC_DTS_THERMAL
 	tristate "Intel SoCs DTS thermal driver"
 	depends on X86 && PCI && ACPI
 	select INTEL_SOC_DTS_IOSF_CORE
-	select THERMAL_WRITABLE_TRIPS
 	help
 	  Enable this to register Intel SoCs (e.g. Bay Trail) platform digital
 	  temperature sensor (DTS). These SoCs have two additional DTSs in

drivers/thermal/thermal_sysfs.c

@@ -458,8 +458,7 @@ static int create_trip_attrs(struct thermal_zone_device *tz, int mask)
 						tz->trip_temp_attrs[indx].name;
 		tz->trip_temp_attrs[indx].attr.attr.mode = S_IRUGO;
 		tz->trip_temp_attrs[indx].attr.show = trip_point_temp_show;
-		if (IS_ENABLED(CONFIG_THERMAL_WRITABLE_TRIPS) &&
-		    mask & (1 << indx)) {
+		if (mask & (1 << indx)) {
 			tz->trip_temp_attrs[indx].attr.attr.mode |= S_IWUSR;
 			tz->trip_temp_attrs[indx].attr.store =
 							trip_point_temp_store;