[G/OEM-5.10] [PATCH 1/7] thermal/core: Emit a warning if the thermal zone is updated without ops

[Kai-Heng Feng]

From: Daniel Lezcano <daniel.lezcano at linaro.org>

BugLink: https://bugs.launchpad.net/bugs/1906168

The actual code is silently ignoring a thermal zone update when a
driver is requesting it without a get_temp ops set.

That looks not correct, as the caller should not have called this
function if the thermal zone is unable to read the temperature.

That makes the code less robust as the check won't detect the driver
is inconsistently using the thermal API and that does not help to
improve the framework as these circumvolutions hide the problem at the
source.

In order to detect the situation when it happens, let's add a warning
when the update is requested without the get_temp() ops set.

Any warning emitted will have to be fixed at the source of the
problem: the caller must not call thermal_zone_device_update if there
is not get_temp callback set.

Cc: Thara Gopinath <thara.gopinath at linaro.org>
Cc: Amit Kucheria <amitk at kernel.org>
Cc: linux-pm at vger.kernel.org
Cc: linux-kernel at vger.kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano at linaro.org>
Reviewed-by: Lukasz Luba <lukasz.luba at arm.com>
Link: https://lore.kernel.org/r/20201210121514.25760-1-daniel.lezcano@linaro.org
(cherry picked from commit 433178e75834dc35f1ae79b56ec2cf396f2c6f3c)
Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
---
 drivers/thermal/thermal_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index b71196eaf90e..749001a88b44 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -467,7 +467,8 @@ void thermal_zone_device_update(struct thermal_zone_device *tz,
 	if (atomic_read(&in_suspend))
 		return;
 
-	if (!tz->ops->get_temp)
+	if (WARN_ONCE(!tz->ops->get_temp, "'%s' must not be called without "
+		      "'get_temp' ops set\n", __func__))
 		return;
 
 	update_temperature(tz);
-- 
2.29.2