From 84872dc448fe0ae11fe8412f4966e9c431a45b8f Mon Sep 17 00:00:00 2001 From: Erwan Le Ray Date: Tue, 18 Jun 2019 12:02:26 +0200 Subject: [PATCH] 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 Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/stm32-usart.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index fd9fb33ce4fe..24a2261f879a 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -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; -- 2.11.0