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drivers: serial: stm32U5 uart driver do not toggle the DMA Tx request

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Errata sheet of the stm32U5 (ES0499) recommends to avoid clearing
the DMAT bit with LL_USART_DisableDMAReq_TX to re-start
a DMA transfer on the UART Tx block. The function becomes empty.
This is also seen for stm32H5.

Signed-off-by: Francois Ramu <francois.ramu@st.com>
This commit is contained in:
Francois Ramu 2023-04-05 16:09:27 +02:00 committed by Carles Cufí
parent ddf518e706
commit 1b2942ffee
1 changed files with 10 additions and 0 deletions
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10
drivers/serial/uart_stm32.c
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@ -1088,9 +1088,19 @@ static inline void uart_stm32_dma_tx_enable(const struct device *dev)
static inline void uart_stm32_dma_tx_disable(const struct device *dev)
{
#if DT_HAS_COMPAT_STATUS_OKAY(st_stm32u5_dma)
ARG_UNUSED(dev);
/*
* Errata Sheet ES0499 : STM32U575xx and STM32U585xx device errata
* USART does not generate DMA requests after setting/clearing DMAT bit
* (also seen on stm32H5 serie)
*/
#else
const struct uart_stm32_config *config = dev->config;
LL_USART_DisableDMAReq_TX(config->usart);
#endif /* ! st_stm32u5_dma */
}
static inline void uart_stm32_dma_rx_enable(const struct device *dev)