Hi Wenbin,
On Tue, Jan 19, 2016 at 6:21 PM, Wenbin Song <wenbin.s...@nxp.com> wrote:
> Hi: Bin,
> Because we use the ns16550 as the early console when booting kernel ,
> and the earlycon driver on kernel cannot initialize port->uartclk rightly,
> So if we want to use it, we must initialize ns16550 on uboot, and use the
> bootargs as follow :
> "console=ttyS0,115200 root=/dev/ram0 earlycon=uart8250,0x21c0500 "
>
I understand this. My question was: U-Boot was booted using LPUART as
its serial console, why do you bother loading a kernel with another
serial port as the early console?
> int __init early_serial8250_setup(struct earlycon_device *device,
> const char *options)
> {
> if (!(device->port.membase || device->port.iobase))
> return -ENODEV;
>
> if (!device->baud) {
> struct uart_port *port = &device->port;
> unsigned int ier;
>
> /* assume the device was initialized, only mask interrupts */
> ier = serial8250_early_in(port, UART_IER);
> serial8250_early_out(port, UART_IER, ier & UART_IER_UUE);
> } else
> init_port(device);
>
> device->con->write = early_serial8250_write;
> return 0;
> }
>
[snip]
Regards,
Bin
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