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arm/stm32h7 add STM32H7_SPI_DMATHRESHOLD

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Daniel Agar 2020-03-02 16:08:11 -05:00 • committed by Abdelatif Guettouche
parent c10fbbbb5f
commit 30a48e4217
2 changed files with 35 additions and 1 deletions
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9
arch/arm/src/stm32h7/Kconfig
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@ -612,6 +612,15 @@ config STM32H7_SPI_DMA
---help---
Use DMA to improve SPI transfer performance. Cannot be used with STM32H7_SPI_INTERRUPT.
config STM32H7_SPI_DMATHRESHOLD
int "SPI DMA threshold"
default 4
depends on STM32H7_SPI_DMA
---help---
When SPI DMA is enabled, small DMA transfers will still be performed
by polling logic. But we need a threshold value to determine what
is small.
endmenu # "SPI Configuration"
menu "U[S]ART Configuration"

27
arch/arm/src/stm32h7/stm32_spi.c
View file

@ -1716,6 +1716,31 @@ static void spi_exchange(FAR struct spi_dev_s *dev, FAR const void *txbuffer,
DEBUGASSERT(priv != NULL);
#ifdef CONFIG_STM32H7_SPI_DMATHRESHOLD
/* Convert the number of word to a number of bytes */
size_t nbytes = (priv->nbits > 8) ? nwords << 1 : nwords;
/* If this is a small SPI transfer, then let spi_exchange_nodma() do the work. */
if (nbytes <= CONFIG_STM32H7_SPI_DMATHRESHOLD)
{
spi_exchange_nodma(dev, txbuffer, rxbuffer, nwords);
return;
}
#endif
if ((priv->rxdma == NULL) || (priv->txdma == NULL) ||
up_interrupt_context())
{
/* Invalid DMA channels, or interrupt context, fall
* back to non-DMA method.
*/
spi_exchange_nodma(dev, txbuffer, rxbuffer, nwords);
return;
}
#ifdef CONFIG_STM32H7_DMACAPABLE
stm32_dmacfg_t dmacfg1;
stm32_dmacfg_t dmacfg2;
@ -1735,7 +1760,7 @@ static void spi_exchange(FAR struct spi_dev_s *dev, FAR const void *txbuffer,
if ((txbuffer && !stm32_dmacapable(priv->txdma, &dmacfg1)) ||
(rxbuffer && !stm32_dmacapable(priv->rxdma, &dmacfg2)))
{
/* Unsupported memory region, fall back to non-DMA method. */
/* Unsupported memory region fall back to non-DMA method. */
spi_exchange_nodma(dev, txbuffer, rxbuffer, nwords);
}