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Commit bd21f551 authored by Flavio Leitner's avatar Flavio Leitner Committed by Greg Kroah-Hartman
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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: default avatarFlavio Leitner <fbl@redhat.com>
Acked-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 05fb79e4

drivers/tty/serial/8250/8250.c

+14 −11
Original line number Diff line number Diff line
@@ -1037,6 +1037,7 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags) 
	unsigned char save_lcr, save_mcr;

	struct uart_port *port = &up->port;

	unsigned long flags;

	unsigned int old_capabilities;



	if (!port->iobase && !port->mapbase && !port->membase)

		return;
@@ -1087,6 +1088,7 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags) 
			/*

			 * We failed; there's nothing here

			 */

			spin_unlock_irqrestore(&port->lock, flags);

			DEBUG_AUTOCONF("IER test failed (%02x, %02x) ",

				       scratch2, scratch3);

			goto out;
@@ -1110,6 +1112,7 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags) 
		status1 = serial_in(up, UART_MSR) & 0xF0;

		serial_out(up, UART_MCR, save_mcr);

		if (status1 != 0x90) {

			spin_unlock_irqrestore(&port->lock, flags);

			DEBUG_AUTOCONF("LOOP test failed (%02x) ",

				       status1);

			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);

	scratch = serial_in(up, UART_IIR) >> 6;



	DEBUG_AUTOCONF("iir=%d ", scratch);



	switch (scratch) {

	case 0:

		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);



	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;

	old_capabilities = up->capabilities; 

	up->capabilities = uart_config[port->type].flags;

	up->tx_loadsz = uart_config[port->type].tx_loadsz;



	if (port->type == PORT_UNKNOWN)

		goto out;

		goto out_lock;



	/*

	 * Reset the UART.
@@ -1196,8 +1191,16 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags) 
	else

		serial_out(up, UART_IER, 0);



 out:

out_lock:

	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);

}