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serial: 8250_early: Assume uart already initialized if no baud option

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The <baud><parity><bit> option string is not supplied if the earlycon
is started via devicetree and OF_EARLYCON_DECLARE(). The option string
is also not required if started via kernel command line parameters of
the form:
  earlycon=uart,mmio,<addr>
  console=uart,mmio,<addr>

If earlycon_device->baud is 0, then an option string was not supplied.
In this case, assume the uart has already been initialized by the
bootloader or firmware.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2015-03-09 16:27:16 -04:00 committed by Greg Kroah-Hartman
parent feed5bab0d
commit 0e3e143e5d
1 changed files with 8 additions and 2 deletions
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10
drivers/tty/serial/8250/8250_early.c
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@ -149,12 +149,18 @@ static int __init early_serial8250_setup(struct earlycon_device *device,
return 0;
if (!device->baud) {
struct uart_port *port = &device->port;
unsigned int ier;
device->baud = probe_baud(&device->port);
snprintf(device->options, sizeof(device->options), "%u",
device->baud);
}
init_port(device);
/* 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;