Commit 5f5c9ae56c
"serial_core: Unregister console in uart_remove_one_port()"
fixed a crash where a serial port was removed but
not deregistered as a console.
There is a side effect of that commit for platforms having serial consoles
and of_serial configured (CONFIG_SERIAL_OF_PLATFORM). The serial console
is disabled midway through the boot process.
This cessation of the serial console affects PowerPC computers
such as the MVME5100 and SAM440EP.
The sequence is:
bootconsole [udbg0] enabled
....
serial8250/16550 driver initialises and registers its UARTS,
one of these is the serial console.
console [ttyS0] enabled
....
of_serial probes "platform" devices, registering them as it goes.
One of these is the serial console.
console [ttyS0] disabled.
The disabling of the serial console is due to:
a. unregister_console in printk not clearing the
CONS_ENABLED bit in the console flags,
even though it has announced that the console is disabled; and
b. of_platform_serial_probe in of_serial not setting the port type
before it registers with serial8250_register_8250_port.
This patch ensures that the serial console is re-enabled when of_serial
registers a serial port that corresponds to the designated console.
Signed-off-by: Stephen Chivers <schivers@csc.com>
Tested-by: Stephen Chivers <schivers@csc.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [unregister_console]
Cc: stable <stable@vger.kernel.org> # 3.15
===
The above failure was identified in Linux-3.15-rc2.
Tested using MVME5100 and SAM440EP PowerPC computers with
kernels built from Linux-3.15-rc5 and tty-next.
The continued operation of the serial console is vital for computers
such as the MVME5100 as that Single Board Computer does not
have any grapical/display hardware.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
7fa21dd8bd