From: Paul Fulghum <paulkf@microgate.com>
Fix lockup caused by 8520 serial driver not clearing receive interrupt if
flip buffer becomes full.
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/drivers/serial/8250.c | 21 ++++++++++++++++++---
1 files changed, 18 insertions(+), 3 deletions(-)
diff -puN drivers/serial/8250.c~serial-8250-receive-lockup-fix drivers/serial/8250.c
--- 25/drivers/serial/8250.c~serial-8250-receive-lockup-fix 2004-11-10 00:47:49.403649968 -0800
+++ 25-akpm/drivers/serial/8250.c 2004-11-10 00:49:14.343737112 -0800
@@ -983,9 +983,24 @@ receive_chars(struct uart_8250_port *up,
do {
if (unlikely(tty->flip.count >= TTY_FLIPBUF_SIZE)) {
tty->flip.work.func((void *)tty);
- if (tty->flip.count >= TTY_FLIPBUF_SIZE)
- return; // if TTY_DONT_FLIP is set
- }
+ if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
+ /*
+ * no room in flip buffer, discard rx FIFO
+ * contents to clear IRQ.
+ * *FIXME* Hardware with auto flow control
+ * would benefit from leaving the data in the
+ * FIFO and disabling the rx IRQ until space
+ * becomes available.
+ */
+ do {
+ serial_inp(up, UART_RX);
+ up->port.icount.overrun++;
+ *status = serial_inp(up, UART_LSR);
+ } while ((*status & UART_LSR_DR) &&
+ (max_count-- > 0));
+ return; /* if TTY_DONT_FLIP is set */
+ }
+ }
ch = serial_inp(up, UART_RX);
*tty->flip.char_buf_ptr = ch;
*tty->flip.flag_buf_ptr = TTY_NORMAL;
_