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drivers: uart_stm32: fix ORE hogging the CPU

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If data is received before an IRQ handler was set and enabled,
hardware sets the ORE flag. Once set, the IRQ routine starts
hogging the CPU until ORE is cleared. This change will clear
the flag when user code attempts to drain incoming data.

Signed-off-by: Kiril Zyapkov <k.zyapkov@allterco.com>
This commit is contained in:
Kiril Zyapkov 2018-11-02 15:34:56 +02:00 • committed by Anas Nashif
commit 7a602fc615
1 changed files with 11 additions and 0 deletions
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11
drivers/serial/uart_stm32.c
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@ -36,6 +36,11 @@ static int uart_stm32_poll_in(struct device *dev, unsigned char *c)
{
USART_TypeDef *UartInstance = UART_STRUCT(dev);
/* Clear overrun error flag */
if (LL_USART_IsActiveFlag_ORE(UartInstance)) {
LL_USART_ClearFlag_ORE(UartInstance);
}
if (!LL_USART_IsActiveFlag_RXNE(UartInstance)) {
return -1;
}
@ -107,6 +112,12 @@ static int uart_stm32_fifo_read(struct device *dev, u8_t *rx_data,
/* Receive a character (8bit , parity none) */
rx_data[num_rx++] = LL_USART_ReceiveData8(UartInstance);
/* Clear overrun error flag */
if (LL_USART_IsActiveFlag_ORE(UartInstance)) {
LL_USART_ClearFlag_ORE(UartInstance);
}
}
return num_rx;
}