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Merge pull request #4717 from gebart/pr/stm32f4-uart-lock

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cpu/stm32f4: Fix DMA race bug (#4716)
This commit is contained in:
Joakim Nohlgård 2016-02-01 09:07:13 +01:00
commit fa273b134e
1 changed files with 10 additions and 6 deletions
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16
cpu/stm32f4/periph/uart.c
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@ -42,7 +42,8 @@ static inline USART_TypeDef *_dev(uart_t uart)
/**
* @brief Transmission locks
*/
static mutex_t tx_sync[UART_NUMOF];
static mutex_t _tx_dma_sync[UART_NUMOF];
static mutex_t _tx_lock[UART_NUMOF];
/**
* @brief Find out which peripheral bus the UART device is connected to
@ -73,9 +74,10 @@ int uart_init(uart_t uart, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)
/* remember callback addresses and argument */
uart_ctx[uart].rx_cb = rx_cb;
uart_ctx[uart].arg = arg;
/* init tx lock */
mutex_init(&tx_sync[uart]);
mutex_lock(&tx_sync[uart]);
/* init TX lock and DMA synchronization mutex */
mutex_init(&_tx_lock[uart]);
mutex_init(&_tx_dma_sync[uart]);
mutex_lock(&_tx_dma_sync[uart]);
/* configure pins */
gpio_init(uart_config[uart].rx_pin, GPIO_DIR_IN, GPIO_NOPULL);
@ -128,13 +130,15 @@ void uart_write(uart_t uart, const uint8_t *data, size_t len)
}
}
else {
mutex_lock(&_tx_lock[uart]);
DMA_Stream_TypeDef *stream = dma_stream(uart_config[uart].dma_stream);
/* configure and start DMA transfer */
stream->M0AR = (uint32_t)data;
stream->NDTR = (uint16_t)len;
stream->CR |= DMA_SxCR_EN;
/* wait for transfer to complete */
mutex_lock(&tx_sync[uart]);
mutex_lock(&_tx_dma_sync[uart]);
mutex_unlock(&_tx_lock[uart]);
}
}
@ -173,7 +177,7 @@ static inline void dma_handler(int uart, int stream)
{
/* clear DMA done flag */
dma_base(stream)->IFCR[dma_hl(stream)] = dma_ifc(stream);
mutex_unlock(&tx_sync[uart]);
mutex_unlock(&_tx_dma_sync[uart]);
if (sched_context_switch_request) {
thread_yield();
}