| From a1b35991075af4f9958476492d622453236f4dec Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Thu, 4 Mar 2021 17:22:58 +0100 |
| Subject: serial: stm32: fix incorrect characters on console |
| |
| From: Erwan Le Ray <erwan.leray@foss.st.com> |
| |
| [ Upstream commit f264c6f6aece81a9f8fbdf912b20bd3feb476a7a ] |
| |
| Incorrect characters are observed on console during boot. This issue occurs |
| when init/main.c is modifying termios settings to open /dev/console on the |
| rootfs. |
| |
| This patch adds a waiting loop in set_termios to wait for TX shift register |
| empty (and TX FIFO if any) before stopping serial port. |
| |
| Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver") |
| Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com> |
| Link: https://lore.kernel.org/r/20210304162308.8984-4-erwan.leray@foss.st.com |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/tty/serial/stm32-usart.c | 12 +++++++++++- |
| 1 file changed, 11 insertions(+), 1 deletion(-) |
| |
| diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c |
| index 909a0d991ba1..70155e0c3b02 100644 |
| --- a/drivers/tty/serial/stm32-usart.c |
| +++ b/drivers/tty/serial/stm32-usart.c |
| @@ -736,8 +736,9 @@ static void stm32_usart_set_termios(struct uart_port *port, |
| unsigned int baud, bits; |
| u32 usartdiv, mantissa, fraction, oversampling; |
| tcflag_t cflag = termios->c_cflag; |
| - u32 cr1, cr2, cr3; |
| + u32 cr1, cr2, cr3, isr; |
| unsigned long flags; |
| + int ret; |
| |
| if (!stm32_port->hw_flow_control) |
| cflag &= ~CRTSCTS; |
| @@ -746,6 +747,15 @@ static void stm32_usart_set_termios(struct uart_port *port, |
| |
| spin_lock_irqsave(&port->lock, flags); |
| |
| + ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr, |
| + isr, |
| + (isr & USART_SR_TC), |
| + 10, 100000); |
| + |
| + /* Send the TC error message only when ISR_TC is not set. */ |
| + if (ret) |
| + dev_err(port->dev, "Transmission is not complete\n"); |
| + |
| /* Stop serial port and reset value */ |
| writel_relaxed(0, port->membase + ofs->cr1); |
| |
| -- |
| 2.30.2 |
| |
