[PATCH v5 2/2] serial: mxc: have putc use the TXFIFO

[Tim Harvey]

On Tue, Oct 25, 2022 at 1:37 PM Fabio Estevam <festevam at denx.de> wrote:
>
> Hi Pali,
>
> On 25/10/2022 17:23, Pali Rohár wrote:
>
> > Hello! I do not have any MXC hardware but I see there one issue.
> > mxc_serial_putc() function probably should not return -EAGAIN when
> > device is busy. But instead it should wait until it is ready.
> >
> > Could you try to change code to following?
> >
> >     while (readl(&uart->ts) & UTS_TXFULL)
> >         ;
> >
> >     writel(ch, &uart->txd);
>
> Your analysis looks correct.
>
> The kernel does like this:
>
> static void imx_uart_console_putchar(struct uart_port *port, unsigned
> char ch)
> {
>         struct imx_port *sport = (struct imx_port *)port;
>
>         while (imx_uart_readl(sport, imx_uart_uts_reg(sport)) & UTS_TXFULL)
>                 barrier();
>
>         imx_uart_writel(sport, ch, URTX0);
> }
>
> Thanks

Fabio and Pali,

Seems reasonable but this does not resolve the problem. Whatever I
print in board_init gets cutoff by the print from dm_announce.

Tim