pkarashchenko commented on code in PR #11020:
URL: https://github.com/apache/nuttx/pull/11020#discussion_r1370501788
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arch/arm/src/imxrt/imxrt_serial.c:
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@@ -2345,14 +2346,26 @@ static bool imxrt_rxflowcontrol(struct uart_dev_s *dev,
#ifdef SERIAL_HAVE_RXDMA
static int imxrt_dma_receive(struct uart_dev_s *dev, unsigned int *status)
{
- struct imxrt_uart_s *priv = (struct imxrt_uart_s *)dev;
- uint32_t nextrx = imxrt_dma_nextrx(priv);
- int c = 0;
+ struct imxrt_uart_s *priv = (struct imxrt_uart_s *)dev;
+ static uint32_t last_nextrx = -1;
+ uint32_t nextrx = imxrt_dma_nextrx(priv);
+ int c = 0;
/* Check if more data is available */
if (nextrx != priv->rxdmanext)
{
+ /* Now we must ensure the cache is updated if the DMA has
+ * updated again.
+ */
+
+ if (last_nextrx != nextrx)
+ {
+ up_invalidate_dcache((uintptr_t)priv->rxfifo,
+ (uintptr_t)priv->rxfifo + RXDMA_BUFFER_SIZE);
+ last_nextrx = nextrx;
+ }
Review Comment:
So we simply can do a read while DMA is running? Is that correct?
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