From 77e433a95698657b20e9929de653f1790abc3501 Mon Sep 17 00:00:00 2001
From: wiechula <Jens.Wiechula@cern.ch>
Date: Wed, 14 Oct 2026 17:16:16 +0200
Subject: [PATCH] Add common mode per pad saturation

The largest common mode per pad is given by the pedestal value. Saturate
the CM signal in case it would be larger.
---
 .../TPC/base/include/TPCBase/ParameterElectronics.h      | 1 +
 .../simulation/include/TPCSimulation/DigitGlobalPad.h    | 4 ++--
 .../TPC/simulation/include/TPCSimulation/DigitTime.h     | 9 +++++++--
 Detectors/TPC/simulation/src/DigitContainer.cxx          | 3 ++-
 4 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/Detectors/TPC/base/include/TPCBase/ParameterElectronics.h b/Detectors/TPC/base/include/TPCBase/ParameterElectronics.h
index 8ada729f36103..31be5103d4d39 100644
--- a/Detectors/TPC/base/include/TPCBase/ParameterElectronics.h
+++ b/Detectors/TPC/base/include/TPCBase/ParameterElectronics.h
@@ -48,6 +48,7 @@ struct ParameterElectronics : public o2::conf::ConfigurableParamHelper<Parameter
   bool doIonTail = false;                                                       ///< add ion tail in simulation
   bool doIonTailPerPad = false;                                                 ///< add ion tail in simulation using pad-by-pad values
   bool doCommonModePerPad = true;                                               ///< add common mode in simulation using pad-by-pad values
+  bool doCommonModePerPadSaturation = true;                                     ///< Saturate the common mode signal by the per pad pedestal value
   bool doSaturationTail = false;                                                ///< add saturation tail in simulation
   bool doNoiseEmptyPads = false;                                                ///< add noise in pads without signal in simulation
   bool applyDeadMap = true;                                                     ///< apply dead channel map
diff --git a/Detectors/TPC/simulation/include/TPCSimulation/DigitGlobalPad.h b/Detectors/TPC/simulation/include/TPCSimulation/DigitGlobalPad.h
index 743dfc3bd6977..66a2d640fdf6b 100644
--- a/Detectors/TPC/simulation/include/TPCSimulation/DigitGlobalPad.h
+++ b/Detectors/TPC/simulation/include/TPCSimulation/DigitGlobalPad.h
@@ -80,7 +80,7 @@ class DigitGlobalPad
                 o2::dataformats::LabelContainer<std::pair<MCCompLabel, int>, false>&);
 
   /// Fold signal with previous pad signal add ion tail and ToT for sigmal saturation
-  void foldSignal(PrevDigitInfo& prevDigit, const int sector, const int pad, const TimeBin time, Streamer* debugStream = nullptr, const CalPad* padParams[3] = nullptr);
+  void foldSignal(PrevDigitInfo& prevDigit, const int sector, const int pad, const TimeBin time, Streamer* debugStream = nullptr, const CalPad* padParams[4] = nullptr);
 
   void setID(int id) { mID = id; }
   int getID() const { return mID; }
@@ -131,7 +131,7 @@ inline void DigitGlobalPad::addDigit(const MCCompLabel& label, float signal,
   mChargePad += signal;
 }
 
-inline void DigitGlobalPad::foldSignal(PrevDigitInfo& prevDigit, const int sector, const int pad, const TimeBin time, Streamer* debugStream, const CalPad* padParams[3])
+inline void DigitGlobalPad::foldSignal(PrevDigitInfo& prevDigit, const int sector, const int pad, const TimeBin time, Streamer* debugStream, const CalPad* padParams[4])
 {
   const auto& eleParam = ParameterElectronics::Instance();
   const auto& itSettings = IonTailSettings::Instance();
diff --git a/Detectors/TPC/simulation/include/TPCSimulation/DigitTime.h b/Detectors/TPC/simulation/include/TPCSimulation/DigitTime.h
index 361b1fb8f6572..c766247759771 100644
--- a/Detectors/TPC/simulation/include/TPCSimulation/DigitTime.h
+++ b/Detectors/TPC/simulation/include/TPCSimulation/DigitTime.h
@@ -129,7 +129,7 @@ inline float DigitTime::getCommonMode(const GEMstack& gemstack) const
 template <DigitzationMode MODE>
 inline void DigitTime::fillOutputContainer(std::vector<Digit>& output, dataformats::MCTruthContainer<MCCompLabel>& mcTruth,
                                            std::vector<CommonMode>& commonModeOutput, const Sector& sector, TimeBin timeBin,
-                                           PrevDigitInfoArray* prevTime, Streamer* debugStream, const CalPad* padParams[3],
+                                           PrevDigitInfoArray* prevTime, Streamer* debugStream, const CalPad* padParams[4],
                                            const CalDet<bool>* deadMap)
 {
   const auto& mapper = Mapper::instance();
@@ -148,7 +148,12 @@ inline void DigitTime::fillOutputContainer(std::vector<Digit>& output, dataforma
     }
     const CRU cru = mapper.getCRU(sector, iPad);
     const float cmKValue = (padParams[2]) ? padParams[2]->getValue(sector.getSector(), iPad) : 1.f;
-    mCommonMode[cru.gemStack()] += digit.getChargePad() * eleParam.commonModeCoupling * cmKValue; // TODO: Add stack-by-stack variation?
+    float commonModeSignal = digit.getChargePad() * eleParam.commonModeCoupling * cmKValue; // TODO: Add stack-by-stack variation?
+    if (eleParam.doCommonModePerPadSaturation) {
+      const float pedestal = (padParams[3]) ? padParams[3]->getValue(sector.getSector(), iPad) : 77.f;
+      commonModeSignal = std::min(commonModeSignal, pedestal);
+    }
+    mCommonMode[cru.gemStack()] += commonModeSignal;
   }
 
   // fill common mode output container
diff --git a/Detectors/TPC/simulation/src/DigitContainer.cxx b/Detectors/TPC/simulation/src/DigitContainer.cxx
index dfff4b91d6451..99e541ddf9115 100644
--- a/Detectors/TPC/simulation/src/DigitContainer.cxx
+++ b/Detectors/TPC/simulation/src/DigitContainer.cxx
@@ -46,7 +46,7 @@ void DigitContainer::fillOutputContainer(std::vector<Digit>& output,
   auto& cdb = CDBInterface::instance();
 
   // ion tail per pad parameters
-  const CalPad* padParams[3] = {nullptr, nullptr, nullptr};
+  const CalPad* padParams[4] = {nullptr, nullptr, nullptr, nullptr};
 
   if (eleParam.doIonTailPerPad) {
     const auto& itSettings = IonTailSettings::Instance();
@@ -59,6 +59,7 @@ void DigitContainer::fillOutputContainer(std::vector<Digit>& output,
   if (eleParam.doCommonModePerPad) {
     padParams[2] = &cdb.getCMkValues();
   }
+  padParams[3] = &cdb.getPedestals();
 
   const bool needsPrevDigArray = eleParam.doIonTail || eleParam.doIonTailPerPad || eleParam.doSaturationTail;
   const bool needsEmptyTimeBins = needsPrevDigArray || eleParam.doNoiseEmptyPads;