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8250: fix autoconfig to work with serial console 

The autoconfig prints messages while holding the
port's spinlock and that causes a deadlock when
using serial console.

Signed-off-by: Flavio Leitner <fbl@redhat.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Flavio Leitner 2012-09-18 16:21:32 -03:00 committed by Greg Kroah-Hartman
parent 05fb79e45e
commit bd21f551c3
1 changed files with 14 additions and 11 deletions
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25
drivers/tty/serial/8250/8250.c
View File

@ -1037,6 +1037,7 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
unsigned char save_lcr, save_mcr; unsigned char save_lcr, save_mcr;
struct uart_port *port = &up->port; struct uart_port *port = &up->port;
unsigned long flags; unsigned long flags;
unsigned int old_capabilities;
if (!port->iobase && !port->mapbase && !port->membase) if (!port->iobase && !port->mapbase && !port->membase)
return; return;
@ -1087,6 +1088,7 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
/* /*
* We failed; there's nothing here * We failed; there's nothing here
*/ */
spin_unlock_irqrestore(&port->lock, flags);
DEBUG_AUTOCONF("IER test failed (%02x, %02x) ", DEBUG_AUTOCONF("IER test failed (%02x, %02x) ",
scratch2, scratch3); scratch2, scratch3);
goto out; goto out;
@ -1110,6 +1112,7 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
status1 = serial_in(up, UART_MSR) & 0xF0; status1 = serial_in(up, UART_MSR) & 0xF0;
serial_out(up, UART_MCR, save_mcr); serial_out(up, UART_MCR, save_mcr);
if (status1 != 0x90) { if (status1 != 0x90) {
spin_unlock_irqrestore(&port->lock, flags);
DEBUG_AUTOCONF("LOOP test failed (%02x) ", DEBUG_AUTOCONF("LOOP test failed (%02x) ",
status1); status1);
goto out; goto out;
@ -1132,8 +1135,6 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO); serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO);
scratch = serial_in(up, UART_IIR) >> 6; scratch = serial_in(up, UART_IIR) >> 6;
DEBUG_AUTOCONF("iir=%d ", scratch);
switch (scratch) { switch (scratch) {
case 0: case 0:
autoconfig_8250(up); autoconfig_8250(up);
@ -1167,19 +1168,13 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
serial_out(up, UART_LCR, save_lcr); serial_out(up, UART_LCR, save_lcr);
if (up->capabilities != uart_config[port->type].flags) {
printk(KERN_WARNING
"ttyS%d: detected caps %08x should be %08x\n",
serial_index(port), up->capabilities,
uart_config[port->type].flags);
}
port->fifosize = uart_config[up->port.type].fifo_size; port->fifosize = uart_config[up->port.type].fifo_size;
old_capabilities = up->capabilities;
up->capabilities = uart_config[port->type].flags; up->capabilities = uart_config[port->type].flags;
up->tx_loadsz = uart_config[port->type].tx_loadsz; up->tx_loadsz = uart_config[port->type].tx_loadsz;
if (port->type == PORT_UNKNOWN) if (port->type == PORT_UNKNOWN)
goto out; goto out_lock;
/* /*
* Reset the UART. * Reset the UART.
@ -1196,8 +1191,16 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
else else
serial_out(up, UART_IER, 0); serial_out(up, UART_IER, 0);
out: out_lock:
spin_unlock_irqrestore(&port->lock, flags); spin_unlock_irqrestore(&port->lock, flags);
if (up->capabilities != old_capabilities) {
printk(KERN_WARNING
"ttyS%d: detected caps %08x should be %08x\n",
serial_index(port), old_capabilities,
up->capabilities);
}
out:
DEBUG_AUTOCONF("iir=%d ", scratch);
DEBUG_AUTOCONF("type=%s\n", uart_config[port->type].name); DEBUG_AUTOCONF("type=%s\n", uart_config[port->type].name);
} }