commit 7b34ee0f125723fa7951d70a3be606fb3586cc3d
author Mike Capps <mikepcapps@gmail.com> Wed May 04 14:16:12 2022 -0400
committer Mike Capps <mikepcapps@gmail.com> Fri May 06 13:15:56 2022 +0000
tree ec61103595f3014d42a4248da34d21c5177efb43
parent 4907dace0bcaa5d6a9c0e989b6d34c03b6094305

monitor: include previous targets and tachs in PEL

To discover the source of certain fan ramp-up failures, this change
outputs the previous 8 targets and tach readings. The strategy is to see
if hardware limitations prevent attaining the targets quickly enough.

Signed-off-by: Mike Capps <mikepcapps@gmail.com>
Change-Id: Ia38867986b8a8a651de5d01766393c07d413273c

monitor/tach_sensor.cpp

diff --git a/monitor/tach_sensor.cpp b/monitor/tach_sensor.cpp
index 36b20b1..0ff1828 100644
--- a/monitor/tach_sensor.cpp
+++ b/monitor/tach_sensor.cpp
@@ -38,6 +38,8 @@
 
 constexpr auto FAN_TARGET_PROPERTY = "Target";
 constexpr auto FAN_VALUE_PROPERTY = "Value";
+constexpr auto MAX_PREV_TACHS = 8;
+constexpr auto MAX_PREV_TARGETS = 8;
 
 namespace fs = std::filesystem;
 using InternalFailure =
@@ -88,6 +90,13 @@
     // Query functional state from inventory
     // TODO - phosphor-fan-presence/issues/25
 
+    _prevTachs.resize(MAX_PREV_TACHS);
+
+    if (_hasTarget)
+    {
+        _prevTargets.resize(MAX_PREV_TARGETS);
+    }
+
     _functional = true;
 
     try
@@ -177,7 +186,20 @@
     if (_hasTarget)
     {
         readProperty(_interface, FAN_TARGET_PROPERTY, _name, _bus, _tachTarget);
+
+        // record previous target value
+        if (_prevTargets.front() != _tachTarget)
+        {
+            _prevTargets.push_front(_tachTarget);
+
+            _prevTargets.pop_back();
+        }
     }
+
+    // record previous tach value
+    _prevTachs.push_front(_tachInput);
+
+    _prevTachs.pop_back();
 }
 
 std::string TachSensor::getMatchString(const std::string& interface)
@@ -277,6 +299,14 @@
 
     // Check all tach sensors on the fan against the target
     _fan.tachChanged();
+
+    // record previous target value
+    if (_prevTargets.front() != _tachTarget)
+    {
+        _prevTargets.push_front(_tachTarget);
+
+        _prevTargets.pop_back();
+    }
 }
 
 void TachSensor::handleTachChange(sdbusplus::message::message& msg)
@@ -286,6 +316,11 @@
 
     // Check just this sensor against the target
     _fan.tachChanged(*this);
+
+    // record previous tach value
+    _prevTachs.push_front(_tachInput);
+
+    _prevTachs.pop_back();
 }
 
 void TachSensor::startTimer(TimerMode mode)