[GitHub] [incubator-nuttx] raiden00pl commented on a change in pull request #2270: nRF52 SPI improvements

[GitBox]

raiden00pl commented on a change in pull request #2270:
URL: https://github.com/apache/incubator-nuttx/pull/2270#discussion_r520335981



##########
File path: arch/arm/src/nrf52/nrf52_spi.c
##########
@@ -983,51 +1089,86 @@ static void nrf52_spi_exchange(FAR struct spi_dev_s *dev,
 
       regval = (uint32_t)txbuffer;
       nrf52_spi_putreg(priv, NRF52_SPIM_TXDPTR_OFFSET, regval);
-
-      /* Write number of bytes in TXD buffer */
-
-      regval = nwords;
-      nrf52_spi_putreg(priv, NRF52_SPIM_TXDMAXCNT_OFFSET, regval);
     }
   else
     {
       nrf52_spi_putreg(priv, NRF52_SPIM_TXDMAXCNT_OFFSET, 0);
     }
 
-  /* SPI start */
+  /* If more than 255 bytes, enable list mode to send data
+   * in batches
+   */
+
+  if (nwords > 0xff)
+    {
+      if (rxbuffer != NULL)
+        {
+          nrf52_spi_putreg(priv, NRF52_SPIM_RXDLIST_OFFSET, 1);
+        }
+
+      if (txbuffer != NULL)
+        {
+          nrf52_spi_putreg(priv, NRF52_SPIM_TXDLIST_OFFSET, 1);
+        }
+    }
+
+  while (nwords_left > 0)
+    {
+      size_t transfer_size = (nwords_left > 255 ? 255 : nwords_left);
 
-  nrf52_spi_putreg(priv, NRF52_SPIM_TASK_START_OFFSET, SPIM_TASKS_START);
+      if (rxbuffer != NULL)
+        {
+          /* Write number of bytes in RXD buffer */
 
-#ifndef CONFIG_NRF52_SPI_MASTER_INTERRUPTS
-  /* Wait for RX done and TX done */
+          nrf52_spi_putreg(priv, NRF52_SPIM_RXDMAXCNT_OFFSET, transfer_size);
+        }
 
-  while (nrf52_spi_getreg(priv, NRF52_SPIM_EVENTS_END_OFFSET) != 1);
+      if (txbuffer != NULL)
+        {
+          /* Write number of bytes in TXD buffer */
 
-  /* Clear event */
+          nrf52_spi_putreg(priv, NRF52_SPIM_TXDMAXCNT_OFFSET, transfer_size);
+        }
 
-  nrf52_spi_putreg(priv, NRF52_SPIM_EVENTS_END_OFFSET, 0);
-#else
-  /* Wait for transfer complete */
+      /* SPI start */
 
-  nxsem_wait(&priv->sem_isr);
-#endif
+      nrf52_spi_putreg(priv, NRF52_SPIM_TASK_START_OFFSET, SPIM_TASKS_START);
 
-  if (nrf52_spi_getreg(priv, NRF52_SPIM_TXDAMOUNT_OFFSET) != nwords)
-    {
-      spierr("Incomplete transfer wrote %d expected %d\n", regval, nwords);
-    }
+    #ifndef CONFIG_NRF52_SPI_MASTER_INTERRUPTS

Review comment:
       ```suggestion
   #ifndef CONFIG_NRF52_SPI_MASTER_INTERRUPTS
   ```




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