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serial: stm32: add RX and TX FIFO flush 

Adds a flush of RX and TX FIFOs, and fixes some errors:
- adds RX FIFO flush in startup fonction
- removes the useless transmitter enabling in startup fonction
  (e.g. receiver only, see Documentation/serial/driver)
- configures FIFO threshold before enabling it, rather than after
- flushes both TX and RX in set_termios function

Signed-off-by: Erwan Le Ray <erwan.leray@st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
alistair/sunxi64-5.4-dsi
Erwan Le Ray 2019-06-18 12:02:26 +02:00 committed by Greg Kroah-Hartman
parent d0a6a7bcc3
commit 84872dc448
1 changed files with 15 additions and 5 deletions
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20
drivers/tty/serial/stm32-usart.c
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@ -599,11 +599,11 @@ static int stm32_startup(struct uart_port *port)
if (ret)
return ret;
val = stm32_port->cr1_irq | USART_CR1_TE | USART_CR1_RE;
if (stm32_port->fifoen)
val |= USART_CR1_FIFOEN;
stm32_set_bits(port, ofs->cr1, val);
/* RX FIFO Flush */
if (ofs->rqr != UNDEF_REG)
stm32_set_bits(port, ofs->rqr, USART_RQR_RXFRQ);
/* Tx and RX FIFO configuration */
if (stm32_port->fifoen) {
val = readl_relaxed(port->membase + ofs->cr3);
val &= ~(USART_CR3_TXFTCFG_MASK | USART_CR3_RXFTCFG_MASK);
@ -612,6 +612,12 @@ static int stm32_startup(struct uart_port *port)
writel_relaxed(val, port->membase + ofs->cr3);
}
/* RX FIFO enabling */
val = stm32_port->cr1_irq | USART_CR1_RE;
if (stm32_port->fifoen)
val |= USART_CR1_FIFOEN;
stm32_set_bits(port, ofs->cr1, val);
return 0;
}
@ -694,8 +700,12 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
/* Stop serial port and reset value */
writel_relaxed(0, port->membase + ofs->cr1);
cr1 = USART_CR1_TE | USART_CR1_RE;
/* flush RX & TX FIFO */
if (ofs->rqr != UNDEF_REG)
stm32_set_bits(port, ofs->rqr,
USART_RQR_TXFRQ | USART_RQR_RXFRQ);
cr1 = USART_CR1_TE | USART_CR1_RE;
if (stm32_port->fifoen)
cr1 |= USART_CR1_FIFOEN;
cr2 = 0;