On 4/19/22 10:59, Geert Uytterhoeven wrote:
Hi Valentin,
On Tue, Apr 19, 2022 at 10:54 AM Valentin Caron
<valentin.caron@xxxxxxxxxxx> wrote:
Rework stm32_usart_console_putchar() function in order to anticipate
the case where the character can never be sent.
Signed-off-by: Valentin Caron <valentin.caron@xxxxxxxxxxx>
Thanks for your patch!
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -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);
Does it make sense to print this message, i.e. will the user ever see it?
Or is the failure above temporary?
I assume that you have seen this trigger?
+ return;
+ }
writel_relaxed(ch, port->membase + ofs->tdr);
}
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
Hi Geert,
The failure is temporary. It can appears when the uart is too slow to
send data.
I never tested the case, but I prefer to show a message to know if the
console loses a character.
Thanks,
Valentin
