Enable/disable links as needed in CRU driver

Author: PascalBoeschoten

src/Cru/BarAccessor.h

@@ -103,6 +103,12 @@ class BarAccessor
       mBar->writeRegister(Registers::DATA_SOURCE_SELECT.index, source);
     }
 
+    /// Set links
+    void setLinksEnabled(uint32_t mask)
+    {
+      mBar->writeRegister(Registers::LINKS_ENABLE.index, mask);
+    }
+
     /// Gets the serial number from the card.
     /// Note that not all firmwares have a serial number. You should make sure this firmware feature is enabled before
     /// calling this function, or the card may crash. See getFirmwareFeatures().

src/Cru/Constants.h

@@ -49,6 +49,10 @@ static constexpr uintptr_t SUPERPAGES_PUSHED_INTERVAL = 0x4;
 /// Amount of completely pushed superpages
 static constexpr IntervalRegister LINK_SUPERPAGES_PUSHED(0x800, SUPERPAGES_PUSHED_INTERVAL);
 
+/// Enable/disable links
+/// Every bit represents a link. Set a bit to 1 to disable a link.
+static constexpr Register LINKS_ENABLE = 0x604;
+
 /// Configuration register for data generator
 /// Bit 0: set to start data generator
 /// Bits [2:1] determine the data generator pattern

src/Cru/CruDmaChannel.cxx

@@ -90,9 +90,20 @@ CruDmaChannel::~CruDmaChannel()
 void CruDmaChannel::deviceStartDma()
 {
   resetCru();
-  initCru();
-  setBufferReady();
 
+  // Enable links
+  uint32_t mask = 0xFfffFfff;
+  for (const auto& link : mLinks) {
+    Utilities::setBit(mask, link.id, false);
+  }
+  getBar().setLinksEnabled(mask);
+
+  // Set data generator pattern
+  if (mGeneratorEnabled) {
+    getBar().setDataGeneratorPattern(mGeneratorPattern, mGeneratorDataSize, mGeneratorDataSizeRandomEnabled);
+  }
+
+  // Set data source
   if (mGeneratorEnabled) {
     if (mLoopbackMode == LoopbackMode::Internal) {
       if (mFeatures.dataSelection) {
@@ -117,13 +128,16 @@ void CruDmaChannel::deviceStartDma()
     }
   }
 
+  // Initialize link queues
   for (auto &link : mLinks) {
     link.queue.clear();
     link.superpageCounter = 0;
   }
   mReadyQueue.clear();
-
   mLinkQueuesTotalAvailable = LINK_QUEUE_CAPACITY * mLinks.size();
+
+  // Start DMA
+  setBufferReady();
 }
 
 /// Set buffer to ready
@@ -176,14 +190,6 @@ void CruDmaChannel::resetCru()
   std::this_thread::sleep_for(100ms);
 }
 
-void CruDmaChannel::initCru()
-{
-  // Set data generator pattern
-  if (mGeneratorEnabled) {
-    getBar().setDataGeneratorPattern(mGeneratorPattern, mGeneratorDataSize, mGeneratorDataSizeRandomEnabled);
-  }
-}
-
 auto CruDmaChannel::getNextLinkIndex() -> LinkIndex
 {
   auto smallestQueueIndex = std::numeric_limits<LinkIndex>::max();

src/Cru/CruDmaChannel.h

@@ -82,7 +82,6 @@ class CruDmaChannel final : public DmaChannelPdaBase
         SuperpageQueue queue {LINK_QUEUE_CAPACITY};
     };
 
-    void initCru();
     void resetCru();
     void setBufferReady();
     void setBufferNonReady();