commit a734594924c12d0d159c5983c57e95082de32310
author Konstantin Aladyshev <aladyshev22@gmail.com> Wed Apr 28 17:09:02 2021 +0300
committer Ed Tanous <ed@tanous.net> Mon Jul 19 15:04:49 2021 +0000
tree 2c036a6f07f5641feecad208baf8f5602fed02ff
parent 323969bca5b755fdb1f03eeeaf2b399281578d86

hwmontemp: respect 'PowerState' parameter

Currently the hwmontemp app still reads sensor data even when the host
is powered off and a sensor has the '"PowerState": "On"' configuration
parameter. Add a check to the 'setupRead' function to eliminate these
unnecessary read operations.

Tested on the AMD Ethanolx CRB with the SB-TSI sensors.
SB-TSI sensors don't work when the system is in the powered off state.
Moreover, timeout on a value read operation is too long and if the
hwmontemp app is constantly trying to read a sensor value this could
lead to the performance issues.

These commands were used to monitor transactions on the I2C bus:
$ echo 1 > /sys/kernel/debug/tracing/tracing_on
$ echo 1 > /sys/kernel/debug/tracing/events/i2c/i2c_read/enable
$ cat /sys/kernel/debug/tracing/trace_pipe

Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
Change-Id: I47267a006754222f0a869d86fc77dca228633351

include/HwmonTempSensor.hpp

diff --git a/include/HwmonTempSensor.hpp b/include/HwmonTempSensor.hpp
index 4f59af6..5158a26 100644
--- a/include/HwmonTempSensor.hpp
+++ b/include/HwmonTempSensor.hpp
@@ -33,5 +33,6 @@
     unsigned int sensorPollMs;
 
     void handleResponse(const boost::system::error_code& err);
+    void restartRead();
     void checkThresholds(void) override;
 };

src/HwmonTempSensor.cpp

diff --git a/src/HwmonTempSensor.cpp b/src/HwmonTempSensor.cpp
index bd89c4c..667e517 100644
--- a/src/HwmonTempSensor.cpp
+++ b/src/HwmonTempSensor.cpp
@@ -86,8 +86,15 @@
 
 void HwmonTempSensor::setupRead(void)
 {
-    std::weak_ptr<HwmonTempSensor> weakRef = weak_from_this();
+    if (!readingStateGood())
+    {
+        markAvailable(false);
+        updateValue(std::numeric_limits<double>::quiet_NaN());
+        restartRead();
+        return;
+    }
 
+    std::weak_ptr<HwmonTempSensor> weakRef = weak_from_this();
     boost::asio::async_read_until(inputDev, readBuf, '\n',
                                   [weakRef](const boost::system::error_code& ec,
                                             std::size_t /*bytes_transfered*/) {
@@ -100,6 +107,24 @@
                                   });
 }
 
+void HwmonTempSensor::restartRead()
+{
+    std::weak_ptr<HwmonTempSensor> weakRef = weak_from_this();
+    waitTimer.expires_from_now(boost::posix_time::milliseconds(sensorPollMs));
+    waitTimer.async_wait([weakRef](const boost::system::error_code& ec) {
+        if (ec == boost::asio::error::operation_aborted)
+        {
+            return; // we're being canceled
+        }
+        std::shared_ptr<HwmonTempSensor> self = weakRef.lock();
+        if (!self)
+        {
+            return;
+        }
+        self->setupRead();
+    });
+}
+
 void HwmonTempSensor::handleResponse(const boost::system::error_code& err)
 {
     if ((err == boost::system::errc::bad_file_descriptor) ||
@@ -140,28 +165,7 @@
         return; // we're no longer valid
     }
     inputDev.assign(fd);
-    waitTimer.expires_from_now(boost::posix_time::milliseconds(sensorPollMs));
-    std::weak_ptr<HwmonTempSensor> weakRef = weak_from_this();
-    waitTimer.async_wait([weakRef](const boost::system::error_code& ec) {
-        std::shared_ptr<HwmonTempSensor> self = weakRef.lock();
-        if (ec == boost::asio::error::operation_aborted)
-        {
-            if (self)
-            {
-                std::cerr << "Hwmon temp sensor " << self->name
-                          << " read cancelled " << self->path << "\n";
-            }
-            else
-            {
-                std::cerr << "Hwmon sensor read cancelled, no self\n";
-            }
-            return; // we're being canceled
-        }
-        if (self)
-        {
-            self->setupRead();
-        }
-    });
+    restartRead();
 }
 
 void HwmonTempSensor::checkThresholds(void)