From 496c0c4a78431b3a08e8370047d9cfda6202f98a Mon Sep 17 00:00:00 2001
From: Maximiliano Puccio <maximiliano.puccio@cern.ch>
Date: Mon, 10 Feb 2025 18:52:45 +0100
Subject: [PATCH] Flexible config for start layer of ITS tracks

---
 .../ITSMFT/ITS/tracking/include/ITStracking/Configuration.h   | 2 +-
 Detectors/ITSMFT/ITS/tracking/src/TrackerTraits.cxx           | 2 +-
 Detectors/ITSMFT/ITS/tracking/src/TrackingInterface.cxx       | 4 +++-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Detectors/ITSMFT/ITS/tracking/include/ITStracking/Configuration.h b/Detectors/ITSMFT/ITS/tracking/include/ITStracking/Configuration.h
index e99f0c1f4d13f..4dea810fde1b9 100644
--- a/Detectors/ITSMFT/ITS/tracking/include/ITStracking/Configuration.h
+++ b/Detectors/ITSMFT/ITS/tracking/include/ITStracking/Configuration.h
@@ -95,7 +95,7 @@ struct TrackingParameters {
   float MaxChi2ClusterAttachment = 60.f;
   float MaxChi2NDF = 30.f;
   std::vector<float> MinPt = {0.f, 0.f, 0.f, 0.f};
-  unsigned char StartLayerMask = 0x7F;
+  std::vector<unsigned short> StartLayerMask = std::vector<unsigned short>(1, 0xFFFF);
   bool FindShortTracks = false;
   bool PerPrimaryVertexProcessing = false;
   bool SaveTimeBenchmarks = false;
diff --git a/Detectors/ITSMFT/ITS/tracking/src/TrackerTraits.cxx b/Detectors/ITSMFT/ITS/tracking/src/TrackerTraits.cxx
index 8dcb7bfd315c1..199ccfe335f71 100644
--- a/Detectors/ITSMFT/ITS/tracking/src/TrackerTraits.cxx
+++ b/Detectors/ITSMFT/ITS/tracking/src/TrackerTraits.cxx
@@ -573,7 +573,7 @@ void TrackerTraits::findRoads(const int iteration)
     const int minimumLayer{startLevel - 1};
     std::vector<CellSeed> trackSeeds;
     for (int startLayer{mTrkParams[iteration].CellsPerRoad() - 1}; startLayer >= minimumLayer; --startLayer) {
-      if ((mTrkParams[iteration].StartLayerMask & (1 << (startLayer + 2))) == 0) {
+      if ((mTrkParams[iteration].StartLayerMask[mTrkParams[iteration].NLayers - (startLevel + 2)] & (1 << (startLayer + 2))) == 0) {
         continue;
       }
       CA_DEBUGGER(std::cout << "\t\t > Starting processing layer " << startLayer << std::endl);
diff --git a/Detectors/ITSMFT/ITS/tracking/src/TrackingInterface.cxx b/Detectors/ITSMFT/ITS/tracking/src/TrackingInterface.cxx
index 7305e205ecb3a..b1ad0a9e966e7 100644
--- a/Detectors/ITSMFT/ITS/tracking/src/TrackingInterface.cxx
+++ b/Detectors/ITSMFT/ITS/tracking/src/TrackingInterface.cxx
@@ -48,12 +48,14 @@ void ITSTrackingInterface::initialise()
     trackParams[2].CellDeltaTanLambdaSigma *= 4.;
     trackParams[2].MinTrackLength = 4;
     trackParams[2].MinPt[3] = 0.2f;
-    trackParams[2].StartLayerMask = (1 << 6) + (1 << 3);
+    trackParams[2].StartLayerMask = std::vector<unsigned short>(trackParams[2].NLayers - trackParams[2].MinTrackLength + 1, 0x7F);
+    trackParams[2].StartLayerMask[3] = (1 << 6) + (1 << 3);
     if (o2::its::TrackerParamConfig::Instance().doUPCIteration) {
       trackParams[3].TrackletMinPt = 0.1f;
       trackParams[3].CellDeltaTanLambdaSigma *= 4.;
       trackParams[3].MinTrackLength = 4;
       trackParams[3].DeltaROF = 0; // UPC specific setting
+      trackParams[3].StartLayerMask = std::vector<unsigned short>(trackParams[2].NLayers - trackParams[2].MinTrackLength + 1, 0x7F);
     }
     for (auto& param : trackParams) {
       param.ZBins = 64;