Hi Geert, Geert Uytterhoeven wrote, > Hi Waldemar, > > On Fri, May 16, 2014 at 3:49 PM, Waldemar Brodkorb <wbx@xxxxxxxxxxx> wrote: > > I am trying to bootup my Mikrotik RB532 board with the latest > > kernel, but my serial console is disabled after boot: > > .. > > Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled > > serial8250: ttyS0 at MMIO 0x0 (irq = 104, base_baud = 12499875) is a > > 16550A > > console [ttyS0] enabled > > console [ttyS0] disabled > > > > I used git bisect to find the problematic commit: > > commit 5f5c9ae56c38942623f69c3e6dc6ec78e4da2076 > > Author: Geert Uytterhoeven <geert+renesas@xxxxxxxxxxxxxx> > > Date: Fri Feb 28 14:21:32 2014 +0100 > > > > serial_core: Unregister console in uart_remove_one_port() > > > > If the serial port being removed is used as a console, it must > > also be > > unregistered from the console subsystem using > > unregister_console(). > > > > uart_ops.release_port() will release resources (e.g. iounmap() > > the serial > > port registers), causing a crash on subsequent kernel output if > > the console > > is still registered. > > > > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxxxxxxx> > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > > > After reverting the change, everything is fine. > > Does this patch help? https://lkml.org/lkml/2014/5/10/9 The second change in printk.c didn't help. > I guess you're not using of_serial? No, I am not. > Your serial driver may need to set port.type too, if it doesn't already do so > and the type is PORT_UNKNOWN on re-registration. Tried following patch, but it didn't work: diff -Nur linux-3.15-rc5.orig/arch/mips/rb532/serial.c linux-3.15-rc5/arch/mips/rb532/serial.c --- linux-3.15-rc5.orig/arch/mips/rb532/serial.c 2014-05-09 22:10:52.000000000 +0200 +++ linux-3.15-rc5/arch/mips/rb532/serial.c 2014-05-19 20:35:08.000000000 +0200 @@ -37,7 +37,7 @@ extern unsigned int idt_cpu_freq; static struct uart_port rb532_uart = { - .flags = UPF_BOOT_AUTOCONF, + .type = PORT_16550A, .line = 0, .irq = UART0_IRQ, .iotype = UPIO_MEM, diff -Nur linux-3.15-rc5.orig/kernel/printk/printk.c linux-3.15-rc5/kernel/printk/printk.c --- linux-3.15-rc5.orig/kernel/printk/printk.c 2014-05-09 22:10:52.000000000 +0200 +++ linux-3.15-rc5/kernel/printk/printk.c 2014-05-20 09:39:54.000000000 +0200 @@ -2413,6 +2413,7 @@ if (console_drivers != NULL && console->flags & CON_CONSDEV) console_drivers->flags |= CON_CONSDEV; + console->flags &= ~CON_ENABLED; console_unlock(); console_sysfs_notify(); return res; best regards Waldemar
