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author | Stephen Chivers <schivers@csc.com> | 2014-05-14 08:04:39 +1000 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-05-28 13:07:27 -0700 |
commit | 7fa21dd8bd191564a195291161d6b43db5d9c350 (patch) | |
tree | fa2e01328a932ad906f3bb6f704973dda716c9ea /kernel/printk | |
parent | d4089a332883ad969700aac5dd4dd5f1c4fee825 (diff) | |
download | linux-stable-7fa21dd8bd191564a195291161d6b43db5d9c350.tar.gz linux-stable-7fa21dd8bd191564a195291161d6b43db5d9c350.tar.bz2 linux-stable-7fa21dd8bd191564a195291161d6b43db5d9c350.zip |
printk/of_serial: fix serial console cessation part way through boot.
Commit 5f5c9ae56c38942623f69c3e6dc6ec78e4da2076
"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>
Diffstat (limited to 'kernel/printk')
-rw-r--r-- | kernel/printk/printk.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index a45b50962295..81c71617ea28 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2413,6 +2413,7 @@ int unregister_console(struct console *console) if (console_drivers != NULL && console->flags & CON_CONSDEV) console_drivers->flags |= CON_CONSDEV; + console->flags &= ~CON_ENABLED; console_unlock(); console_sysfs_notify(); return res; |