thermal: gov_power_allocator: Allow binding without trip points

[ Upstream commit da781936e7c301e6197eb6513775748e79fb2575 ]

IPA probe function was recently refactored to perform extra error checks
and make sure the thermal zone has trip points necessary for the IPA
operation. With this change, if a thermal zone is probed such that it
has no trip points that IPA can use, IPA will fail and the TZ won't be
created. This is the case if a platform defines a TZ without cooling
devices and only with "hot"/"critical" trip points, often found on some
Qualcomm devices [1].

Documentation across IPA code (notably get_governor_trips() kerneldoc)
suggests that IPA is supposed to handle such TZ even if it won't
actually do anything.

This commit partially reverts the previous change to allow IPA to bind
to such "empty" thermal zones.

Fixes: e83747c2f8e3 ("thermal: gov_power_allocator: Set up trip points earlier")
Link: arch/arm64/boot/dts/qcom/sc7180.dtsi#n4776 # [1]
Signed-off-by: Nikita Travkin <nikita@trvn.ru>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c
index 207a6a3936b54a2b8e2fb5e72b8546c6567fa5ab..38581583ad2896a220324635aaded3fdb6ad6cc1 100644 (file)
--- a/drivers/thermal/gov_power_allocator.c
+++ b/drivers/thermal/gov_power_allocator.c
@@ -679,11 +679,6 @@ static int power_allocator_bind(struct thermal_zone_device *tz)
                return -ENOMEM;
 
        get_governor_trips(tz, params);
-       if (!params->trip_max) {
-               dev_warn(&tz->device, "power_allocator: missing trip_max\n");
-               kfree(params);
-               return -EINVAL;
-       }
 
        ret = check_power_actors(tz, params);
        if (ret < 0) {
@@ -712,9 +707,10 @@ static int power_allocator_bind(struct thermal_zone_device *tz)
        if (!tz->tzp->sustainable_power)
                dev_warn(&tz->device, "power_allocator: sustainable_power will be estimated\n");
 
-       estimate_pid_constants(tz, tz->tzp->sustainable_power,
-                              params->trip_switch_on,
-                              params->trip_max->temperature);
+       if (params->trip_max)
+               estimate_pid_constants(tz, tz->tzp->sustainable_power,
+                                      params->trip_switch_on,
+                                      params->trip_max->temperature);
 
        reset_pid_controller(params);