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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: Aristeu Rozanski <arozansk@redhat.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Aristeu Rozanski 2008-07-23 21:29:45 -07:00 committed by Linus Torvalds
parent 920519c1c3
commit 7500b1f602
1 changed files with 14 additions and 3 deletions
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17
drivers/serial/8250.c
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@ -1293,7 +1293,18 @@ receive_chars(struct uart_8250_port *up, unsigned int *status)
char flag;
do {
ch = serial_inp(up, UART_RX);
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)