Commit 28fb1a92 authored by Valentin Caron's avatar Valentin Caron Committed by Greg Kroah-Hartman
Browse files

serial: stm32: remove infinite loop possibility in putchar function 



Rework stm32_usart_console_putchar() function in order to anticipate
the case where the character can never be sent.

Signed-off-by: default avatarValentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20220419085330.1178925-2-valentin.caron@foss.st.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ec66b8cf

drivers/tty/serial/stm32-usart.c

+9 −3
Original line number Diff line number Diff line
@@ -1640,10 +1640,16 @@ static void stm32_usart_console_putchar(struct uart_port *port, unsigned char ch 
{

	struct stm32_port *stm32_port = to_stm32_port(port);

	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;

	u32 isr;

	int ret;



	while (!(readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE))

		cpu_relax();



	ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr, isr,

						(isr & USART_SR_TXE), 100,

						STM32_USART_TIMEOUT_USEC);

	if (ret != 0) {

		dev_err(port->dev, "Error while sending data in UART TX : %d\n", ret);

		return;

	}

	writel_relaxed(ch, port->membase + ofs->tdr);

}

drivers/tty/serial/stm32-usart.h

+2 −0
Original line number Diff line number Diff line
@@ -251,6 +251,8 @@ struct stm32_usart_info stm32h7_info = { 
#define RX_BUF_P (RX_BUF_L / 2)	 /* dma rx buffer period     */

#define TX_BUF_L RX_BUF_L	 /* dma tx buffer length     */



#define STM32_USART_TIMEOUT_USEC USEC_PER_SEC /* 1s timeout in µs */



struct stm32_port {

	struct uart_port port;

	struct clk *clk;