Hi Valentin,
On Tue, Apr 19, 2022 at 10:54 AM Valentin Caron
<[email protected]> 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 <[email protected]>
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 -- [email protected]
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
On 4/19/22 10:59, Geert Uytterhoeven wrote:
> Hi Valentin,
>
> On Tue, Apr 19, 2022 at 10:54 AM Valentin Caron
> <[email protected]> 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 <[email protected]>
> 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 -- [email protected]
>
> 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