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serial: stm32: add FIFO flush when port is closed

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[ Upstream commit 9f77d19207 ]

Transmission complete error is sent when ISR_TC is not set. If port closure
is requested despite data in TDR / TX FIFO has not been sent (because of
flow control), ISR_TC is not set and error message is sent on port closure
but also when a new port is opened.

Flush the data when port is closed, so the error isn't printed twice upon
next port opening.

Fixes: 64c32eab66 ("serial: stm32: Add support of TC bit status check")
Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com>
Link: https://lore.kernel.org/r/20210304162308.8984-12-erwan.leray@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Erwan Le Ray 2021-03-04 17:23:06 +01:00 • committed by Greg Kroah-Hartman
commit 566901ba50
1 changed files with 5 additions and 0 deletions
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5
drivers/tty/serial/stm32-usart.c
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@ -689,6 +689,11 @@ static void stm32_usart_shutdown(struct uart_port *port)
if (ret)
dev_err(port->dev, "transmission complete not set\n");
/* flush RX & TX FIFO */
if (ofs->rqr != UNDEF_REG)
writel_relaxed(USART_RQR_TXFRQ | USART_RQR_RXFRQ,
port->membase + ofs->rqr);
stm32_usart_clr_bits(port, ofs->cr1, val);
free_irq(port->irq, port);