FanController/ThermalController: Clean up PID input math
Adding checking against floating-point oddities,
such as NAN, +INF, or -INF, appearing as input,
which would mess up the PID loop math,
causing corrupt output.
If a fan or thermal input value is NAN, +INF, or -INF,
that value will be omitted from contributing to PID loop input.
If all values were omitted for that PID loop,
existing code already hardcodes a value of 0 for fan,
and I added similar code to also hardcode 0 for thermal.
It makes sense to use a placeholder value of 0 degrees of margin,
because this will make the fans spin fast,
if for some reason the zone is not already in failsafe mode by now.
Note that negative values are not allowed for fan,
but they are allowed for thermal.
Tested: Works for me, and PID loops no longer output garbage
when debugging a sensor malfunction while in tuning mode,
making tuning mode much more usable. If not in tuning mode,
the normal failsafe feature would have kicked in,
masking this garbage from appearing in the output anyway.
Signed-off-by: Josh Lehan <krellan@google.com>
Change-Id: I7aee812ebaeff209f84cef0db28973696f782ef9
diff --git a/pid/thermalcontroller.cpp b/pid/thermalcontroller.cpp
index 35dcd15..8125349 100644
--- a/pid/thermalcontroller.cpp
+++ b/pid/thermalcontroller.cpp
@@ -21,6 +21,8 @@
#include "zone.hpp"
#include <algorithm>
+#include <cmath>
+#include <iostream>
namespace pid_control
{
@@ -75,9 +77,25 @@
compare = std::max<double>;
}
+ bool acceptable = false;
for (const auto& in : _inputs)
{
- value = compare(value, _owner->getCachedValue(in));
+ double cachedValue = _owner->getCachedValue(in);
+
+ // Less than 0 is perfectly OK for temperature, but must not be NAN
+ if (!(std::isfinite(cachedValue)))
+ {
+ continue;
+ }
+
+ value = compare(value, cachedValue);
+ acceptable = true;
+ }
+
+ if (!acceptable)
+ {
+ // While not optimal, zero is better than garbage
+ value = 0;
}
return value;