On 16/02/16 10:36, Andy Shevchenko wrote: > On Tue, Feb 16, 2016 at 12:08 PM, Vladimir Murzin > <vladimir.murzin@xxxxxxx> wrote: >> This adds support early console for MPS2 UART which can be enabled via >> earlycon=mps2,0x40004000 > > >> --- a/drivers/tty/serial/mps2-uart.c >> +++ b/drivers/tty/serial/mps2-uart.c >> @@ -435,6 +435,36 @@ static struct console mps2_uart_console = { >> >> #define MPS2_SERIAL_CONSOLE (&mps2_uart_console) >> >> +static void mps2_early_putchar(struct uart_port *port, int ch) >> +{ >> + >> + while (readb(port->membase + UARTn_STATE) & UARTn_STATE_TX_FULL) >> + cpu_relax(); > > Infinite busy loop? In case of broken hw, yes, but I'm quite unsure how we can help to fix it. Do you have something in mind? > >> + >> + writeb((unsigned char)ch, port->membase + UARTn_DATA); >> +} >> + >> + >> +static void mps2_early_write(struct console *con, const char *s, unsigned n) >> +{ >> + struct earlycon_device *dev = con->data; >> + >> + uart_console_write(&dev->port, s, n, mps2_early_putchar); >> +} >> + >> +static int __init mps2_early_console_setup(struct earlycon_device *device, >> + const char *opt) >> +{ >> + if (!device->port.membase) >> + return -ENODEV; >> + >> + device->con->write = mps2_early_write; >> + >> + return 0; >> +} >> +EARLYCON_DECLARE(mps2, mps2_early_console_setup); >> +OF_EARLYCON_DECLARE(mps2, "arm,mps2-uart", mps2_early_console_setup); > > IIRC Peter Hurley mentioned you don't need to put both anymore, OF_ > one is enough. > I've just tried with OF_ only and seems it works fine. Thanks for pointing at it! Cheers Vladimir -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html