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arm/stm32f7 add STM32F7_SPI_DMATHRESHOLD

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Daniel Agar 2020-03-02 16:03:15 -05:00 committed by Abdelatif Guettouche
parent afb2248b7a
commit 608b59792e
2 changed files with 38 additions and 6 deletions
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9
arch/arm/src/stm32f7/Kconfig
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@ -2287,6 +2287,15 @@ config STM32F7_SPI_DMA
---help---
Use DMA to improve SPI transfer performance. Cannot be used with STM32F7_SPI_INTERRUPT.
config STM32F7_SPI_DMATHRESHOLD
int "SPI DMA threshold"
default 4
depends on STM32F7_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.
config STM32F7_SPI1_DMA
bool "SPI1 DMA"
default n

35
arch/arm/src/stm32f7/stm32_spi.c
View File

@ -1646,13 +1646,36 @@ static void spi_exchange(FAR struct spi_dev_s *dev, FAR const void *txbuffer,
DEBUGASSERT(priv != NULL);
#ifdef CONFIG_STM32F7_DMACAPABLE
if ((priv->rxdma == NULL) || (priv->txdma == NULL) ||
(txbuffer && !stm32_dmacapable((uint32_t)txbuffer, nwords, priv->txccr)) ||
(rxbuffer && !stm32_dmacapable((uint32_t)rxbuffer, nwords, priv->rxccr)) ||
up_interrupt_context() || nwords < CONFIG_STM32F7_SPI_DMA_THRESHOLD)
#ifdef CONFIG_STM32F7_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_STM32F7_SPI_DMATHRESHOLD)
{
/* Invalid DMA channels, unsupported memory region, or interrupt context, fall back to non-DMA method. */
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_STM32F7_DMACAPABLE
if ((txbuffer && !stm32_dmacapable((uint32_t)txbuffer, nwords, priv->txccr)) ||
(rxbuffer && !stm32_dmacapable((uint32_t)rxbuffer, nwords, priv->rxccr)))
{
/* Unsupported memory region fall back to non-DMA method. */
spi_exchange_nodma(dev, txbuffer, rxbuffer, nwords);
}