Decreases allowed based on all groups
For speed decreases to occur, all sensor groups involved with setting a
net decrease delta must be below their given t-control low values for
the associated zone. This handles the case where one or more sensor
groups' temperatures stabilize above their t-control low value, but one
or more other sensor groups' temperatures are below their t-control low
value which would result in speed decrease requests that could
eventually lead to fan speed oscillations.
Resolves openbmc/openbmc#2710
Change-Id: I382de5d3f9c3e631a332d49dfcb06e705ff6fc17
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/control/zone.cpp b/control/zone.cpp
index ffde46a..209d773 100644
--- a/control/zone.cpp
+++ b/control/zone.cpp
@@ -270,9 +270,17 @@
void Zone::decTimerExpired()
{
- // Only decrease speeds when no requested increases exist and
- // the increase timer is not running (i.e. not in the middle of increasing)
- if (_incSpeedDelta == 0 && !_incTimer.running())
+ // Check all entries are set to allow a decrease
+ auto pred = [](auto const& entry) {return entry.second;};
+ auto decAllowed = std::all_of(_decAllowed.begin(),
+ _decAllowed.end(),
+ pred);
+
+ // Only decrease speeds when allowed,
+ // where no requested increases exist and
+ // the increase timer is not running
+ // (i.e. not in the middle of increasing)
+ if (decAllowed && _incSpeedDelta == 0 && !_incTimer.running())
{
auto requestTarget = getRequestSpeedBase();
// Request target speed should not start above ceiling