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

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