spiInternalInitStream extract common preInit code.

Clarify logic for init / preinit of spi DMA channels by extracting
the code for when spiInternalInitStream was called with preInit = true.

NB PICO updates to follow

src/main/drivers/bus_spi.c

@@ -490,7 +490,7 @@ void spiSequence(const extDevice_t *dev, busSegment_t *segments)
 FAST_CODE void spiProcessSegmentsDMA(const extDevice_t *dev)
 {
     // Intialise the init structures for the first transfer
-    spiInternalInitStream(dev, false);
+    spiInternalInitStream(dev, dev->bus->curSegment);
 
     // Assert Chip Select
     IOLo(dev->busType_u.spi.csnPin);
@@ -499,6 +499,16 @@ FAST_CODE void spiProcessSegmentsDMA(const extDevice_t *dev)
     spiInternalStartDMA(dev);
 }
 
+static void spiPreInitStream(const extDevice_t *dev)
+{
+    // Prepare the init structure for the next segment to reduce inter-segment interval
+    // (if it's a "buffers" segment, not a "link" segment).
+    busSegment_t *segment = (busSegment_t *)dev->bus->curSegment + 1;
+    if (segment->len > 0) {
+        spiInternalInitStream(dev, segment);
+    }
+}
+
 // Interrupt handler common code for SPI receive DMA completion.
 // Proceed to next segment as required.
 FAST_IRQ_HANDLER void spiIrqHandler(const extDevice_t *dev)
@@ -512,7 +522,7 @@ FAST_IRQ_HANDLER void spiIrqHandler(const extDevice_t *dev)
             // Repeat the last DMA segment
             bus->curSegment--;
             // Reinitialise the cached init values as segment is not progressing
-            spiInternalInitStream(dev, true);
+            spiPreInitStream(dev);
             break;
 
         case BUS_ABORT:
@@ -557,7 +567,7 @@ FAST_IRQ_HANDLER void spiIrqHandler(const extDevice_t *dev)
 
         // After the completion of the first segment setup the init structure for the subsequent segment
         if (bus->initSegment) {
-            spiInternalInitStream(dev, false);
+            spiInternalInitStream(dev, bus->curSegment);
             bus->initSegment = false;
         }
 
@@ -570,7 +580,7 @@ FAST_IRQ_HANDLER void spiIrqHandler(const extDevice_t *dev)
         spiInternalStartDMA(dev);
 
         // Prepare the init structures ready for the next segment to reduce inter-segment time
-        spiInternalInitStream(dev, true);
+        spiPreInitStream(dev);
     }
 }
 

src/main/drivers/bus_spi_impl.h

@@ -87,7 +87,7 @@ typedef struct SPIDevice_s {
 extern spiDevice_t spiDevice[SPIDEV_COUNT];
 
 void spiInitDevice(SPIDevice device);
-void spiInternalInitStream(const extDevice_t *dev, bool preInit);
+void spiInternalInitStream(const extDevice_t *dev, volatile busSegment_t *segment);
 void spiInternalStartDMA(const extDevice_t *dev);
 void spiInternalStopDMA (const extDevice_t *dev);
 void spiInternalResetStream(dmaChannelDescriptor_t *descriptor);

src/platform/APM32/bus_spi_apm32.c

@@ -156,23 +156,11 @@ FAST_CODE bool spiInternalReadWriteBufPolled(SPI_TypeDef *instance, const uint8_
     return true;
 }
 
-void spiInternalInitStream(const extDevice_t *dev, bool preInit)
+void spiInternalInitStream(const extDevice_t *dev, volatile busSegment_t *segment)
 {
     STATIC_DMA_DATA_AUTO uint8_t dummyTxByte = 0xff;
     STATIC_DMA_DATA_AUTO uint8_t dummyRxByte;
     busDevice_t *bus = dev->bus;
-
-    busSegment_t *segment = (busSegment_t *)bus->curSegment;
-
-    if (preInit) {
-        // Prepare the init structure for the next segment to reduce inter-segment interval
-        segment++;
-        if(segment->len == 0) {
-            // There's no following segment
-            return;
-        }
-    }
-
     int len = segment->len;
 
     uint8_t *txData = segment->u.buffers.txData;

src/platform/AT32/bus_spi_at32bsp.c

@@ -156,23 +156,11 @@ bool spiInternalReadWriteBufPolled(spi_type *instance, const uint8_t *txData, ui
     return true;
 }
 
-void spiInternalInitStream(const extDevice_t *dev, bool preInit)
+void spiInternalInitStream(const extDevice_t *dev, volatile busSegment_t *segment)
 {
     STATIC_DMA_DATA_AUTO uint8_t dummyTxByte = 0xff;
     STATIC_DMA_DATA_AUTO uint8_t dummyRxByte;
     busDevice_t *bus = dev->bus;
-
-    volatile busSegment_t *segment = bus->curSegment;
-
-    if (preInit) {
-        // Prepare the init structure for the next segment to reduce inter-segment interval
-        segment++;
-        if(segment->len == 0) {
-            // There's no following segment
-            return;
-        }
-    }
-
     int len = segment->len;
 
     uint8_t *txData = segment->u.buffers.txData;

src/platform/STM32/bus_spi_ll.c

@@ -268,23 +268,11 @@ FAST_CODE bool spiInternalReadWriteBufPolled(SPI_TypeDef *instance, const uint8_
     return true;
 }
 
-void spiInternalInitStream(const extDevice_t *dev, bool preInit)
+void spiInternalInitStream(const extDevice_t *dev, volatile busSegment_t *segment)
 {
     STATIC_DMA_DATA_AUTO uint8_t dummyTxByte = 0xff;
     STATIC_DMA_DATA_AUTO uint8_t dummyRxByte;
     busDevice_t *bus = dev->bus;
-
-    busSegment_t *segment = (busSegment_t *)bus->curSegment;
-
-    if (preInit) {
-        // Prepare the init structure for the next segment to reduce inter-segment interval
-        segment++;
-        if(segment->len == 0) {
-            // There's no following segment
-            return;
-        }
-    }
-
     int len = segment->len;
 
     uint8_t *txData = segment->u.buffers.txData;

src/platform/STM32/bus_spi_stdperiph.c

@@ -162,23 +162,11 @@ bool spiInternalReadWriteBufPolled(SPI_TypeDef *instance, const uint8_t *txData,
     return true;
 }
 
-void spiInternalInitStream(const extDevice_t *dev, bool preInit)
+void spiInternalInitStream(const extDevice_t *dev, volatile busSegment_t *segment)
 {
     STATIC_DMA_DATA_AUTO uint8_t dummyTxByte = 0xff;
     STATIC_DMA_DATA_AUTO uint8_t dummyRxByte;
     busDevice_t *bus = dev->bus;
-
-    volatile busSegment_t *segment = bus->curSegment;
-
-    if (preInit) {
-        // Prepare the init structure for the next segment to reduce inter-segment interval
-        segment++;
-        if(segment->len == 0) {
-            // There's no following segment
-            return;
-        }
-    }
-
     int len = segment->len;
 
     uint8_t *txData = segment->u.buffers.txData;