thermal: gov_bang_bang: Use governor_data to reduce overhead

thermal: gov_bang_bang: Use governor_data to reduce overhead

After running once, the for_each_trip_desc() loop in
bang_bang_manage() is pure needless overhead because it is not going to
make any changes unless a new cooling device has been bound to one of
the trips in the thermal zone or the system is resuming from sleep.

For this reason, make bang_bang_manage() set governor_data for the
thermal zone and check it upfront to decide whether or not it needs to
do anything.

However, governor_data needs to be reset in some cases to let
bang_bang_manage() know that it should walk the trips again, so add an
.update_tz() callback to the governor and make the core additionally
invoke it during system resume.

To avoid affecting the other users of that callback unnecessarily, add
a special notification reason for system resume, THERMAL_TZ_RESUME, and
also pass it to __thermal_zone_device_update() called during system
resume for consistency.

Signed-off-by: Rafael J. Wysocki <[email protected]>
Acked-by: Peter Kästle <[email protected]>
Reviewed-by: Zhang Rui <[email protected]>
Cc: 6.10+ <[email protected]> # 6.10+
Link: https://patch.msgid.link/[email protected]