arch/arm64/src/imx9/imx9_lpspi.c: Small cache operation optimization

There is no need to invalidate the RX buffer before every transfer. It is never gets dirty, so it is good to invalidate initially after allocation, and after each transfer. Signed-off-by: Jukka Laitinen <[email protected]>
nuttxpr · Oct 23, 2024 · cdd1111 · cdd1111
1 parent 6cadfc1
commit cdd1111
Showing 1 changed file with 6 additions and 8 deletions.
diff --git a/arch/arm64/src/imx9/imx9_lpspi.c b/arch/arm64/src/imx9/imx9_lpspi.c
@@ -1386,14 +1386,6 @@ static void imx9_lpspi_exchange(struct spi_dev_s *dev,
                       (uintptr_t)priv->txbuf + nbytes);
     }
 
-  if (rxbuffer)
-    {
-      /* Prepare the RX buffer for DMA */
-
-      up_invalidate_dcache((uintptr_t)priv->rxbuf,
-                           (uintptr_t)priv->rxbuf + nbytes);
-    }
-
   /* Set up the DMA */
 
   adjust = (priv->nbits > 8) ? 2 : 1;
@@ -2079,6 +2071,12 @@ struct spi_dev_s *imx9_lpspibus_initialize(int bus)
           priv->txbuf = imx9_dma_alloc(CONFIG_IMX9_LPSPI_DMA_BUFFER_SIZE);
           priv->rxbuf = imx9_dma_alloc(CONFIG_IMX9_LPSPI_DMA_BUFFER_SIZE);
           DEBUGASSERT(priv->txbuf && priv->rxbuf);
+
+          /* Invalidate the RX buffer area initially */
+
+          up_invalidate_dcache((uintptr_t)priv->rxbuf,
+                               (uintptr_t)priv->rxbuf +
+                               CONFIG_IMX9_LPSPI_DMA_BUFFER_SIZE);
         }
     }
   else