1 files changed, 54 insertions, 0 deletions
diff --git a/meta-openbmc-mods/meta-common/recipes-phosphor/sensors/dbus-sensors/0004-Fan-Tach-Sensor-Threshold-Ignore-Zero.patch b/meta-openbmc-mods/meta-common/recipes-phosphor/sensors/dbus-sensors/0004-Fan-Tach-Sensor-Threshold-Ignore-Zero.patch
new file mode 100644
index 000000000..214fbe888
--- /dev/null
+++ b/meta-openbmc-mods/meta-common/recipes-phosphor/sensors/dbus-sensors/0004-Fan-Tach-Sensor-Threshold-Ignore-Zero.patch
@@ -0,0 +1,54 @@
+From 221aaf1431a01fefb5e7df2461a1c691738a50a7 Mon Sep 17 00:00:00 2001
+From: Zhikui Ren <zhikui.ren@intel.com>
+Date: Fri, 19 Feb 2021 12:14:05 -0800
+Subject: [PATCH] Fan Tach Sensor Threshold Ignore Zero
+
+Currently there are systems that have system fans plugged
+into different fan connectors. Fan present detection is
+not supported in most of these systems. Critical low
+threshold is asserted for the non-utilized fans
+resulting in FSC boost all fans.
+
+Skip threshold checking for fan tach reading less or equal
+to zero. This is a temporary WA until a more robust solution
+is available.
+
+Note: with this workaround a completely non-working fan
+will not be detected. FSC will still boost fans due to other
+constraints if the system can't be cooled with the working fans.
+
+Tested:
+No cr event for the missing fans.
+
+Signed-off-by: Zhikui Ren <zhikui.ren@intel.com>
+---
+ src/TachSensor.cpp | 12 +++++++++---
+ 1 file changed, 9 insertions(+), 3 deletions(-)
+
+diff --git a/src/TachSensor.cpp b/src/TachSensor.cpp
+index c375dbf..e85a2a2 100644
+--- a/src/TachSensor.cpp
++++ b/src/TachSensor.cpp
+@@ -186,10 +186,16 @@ void TachSensor::checkThresholds(void)
+     // WA - treat value <= 0 as not present
+     bool status = false;
+ 
+-    if (redundancy && *redundancy)
++    if (value > 0)
+     {
+-        (*redundancy)
+-            ->update("/xyz/openbmc_project/sensors/fan_tach/" + name, !status);
++        status = thresholds::checkThresholds(this);
++
++        if (redundancy && *redundancy)
++        {
++            (*redundancy)
++                ->update("/xyz/openbmc_project/sensors/fan_tach/" + name,
++                         !status);
++        }
+     }
+ 
+     bool curLed = !status;
+-- 
+2.17.1
+