This is a note to let you know that I've just added the patch titled
printk/of_serial: fix serial console cessation part way through boot.
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From 7fa21dd8bd191564a195291161d6b43db5d9c350 Mon Sep 17 00:00:00 2001
From: Stephen Chivers <schivers@xxxxxxx>
Date: Wed, 14 May 2014 08:04:39 +1000
Subject: 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@xxxxxxx>
Tested-by: Stephen Chivers <schivers@xxxxxxx>
Acked-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> [unregister_console]
Cc: stable <stable@xxxxxxxxxxxxxxx> # 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@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/of_serial.c | 1 +
kernel/printk/printk.c | 1 +
2 files changed, 2 insertions(+)
diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
index 77ec6a147522..68d4455f3cf9 100644
--- a/drivers/tty/serial/of_serial.c
+++ b/drivers/tty/serial/of_serial.c
@@ -173,6 +173,7 @@ static int of_platform_serial_probe(struct platform_device *ofdev)
{
struct uart_8250_port port8250;
memset(&port8250, 0, sizeof(port8250));
+ port.type = port_type;
port8250.port = port;
if (port.fifosize)
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;
--
1.9.0
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