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Commit 7500b1f6 authored by Aristeu Rozanski's avatar Aristeu Rozanski Committed by Linus Torvalds
Browse files

8250: fix break handling for Intel 82571 



Intel 82571 has a "Serial Over LAN" feature that doesn't properly
implements the receiving of break characters.  When a break is received,
it doesn't set UART_LSR_DR and unless another character is received, the
break won't be received by the application.

Signed-off-by: default avatarAristeu Rozanski <arozansk@redhat.com>
Acked-by: default avatarAlan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 920519c1

drivers/serial/8250.c

+14 −3
Original line number Diff line number Diff line
@@ -1293,7 +1293,18 @@ receive_chars(struct uart_8250_port *up, unsigned int *status) 
	char flag;



	do {

		if (likely(lsr & UART_LSR_DR))

			ch = serial_inp(up, UART_RX);

		else

			/*

			 * Intel 82571 has a Serial Over Lan device that will

			 * set UART_LSR_BI without setting UART_LSR_DR when

			 * it receives a break. To avoid reading from the

			 * receive buffer without UART_LSR_DR bit set, we

			 * just force the read character to be 0

			 */

			ch = 0;



		flag = TTY_NORMAL;

		up->port.icount.rx++;
@@ -1342,7 +1353,7 @@ receive_chars(struct uart_8250_port *up, unsigned int *status) 


ignore_char:

		lsr = serial_inp(up, UART_LSR);

	} while ((lsr & UART_LSR_DR) && (max_count-- > 0));

	} while ((lsr & (UART_LSR_DR | UART_LSR_BI)) && (max_count-- > 0));

	spin_unlock(&up->port.lock);

	tty_flip_buffer_push(tty);

	spin_lock(&up->port.lock);
@@ -1425,7 +1436,7 @@ serial8250_handle_port(struct uart_8250_port *up) 


	DEBUG_INTR("status = %x...", status);



	if (status & UART_LSR_DR)

	if (status & (UART_LSR_DR | UART_LSR_BI))

		receive_chars(up, &status);

	check_modem_status(up);

	if (status & UART_LSR_THRE)