Hi:Bin Thanks for your advice! I realize that I can use the lpuart as earlycon on kernel . So I will remove this patch on next vesion.
Thanks
Wenbin Song
Sent from my iPhone
On Jan 19, 2016, at 18:42, Bin Meng bmeng.cn@gmail.com wrote:
Hi Wenbin,
On Tue, Jan 19, 2016 at 6:21 PM, Wenbin Song wenbin.song@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