From: Paul Fulghum <paulkf@microgate.com>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: [PATCH] 8250 receive lockup fix
Date: Fri, 08 Oct 2004 16:02:52 -0500 [thread overview]
Message-ID: <1097269371.2647.2.camel@deimos.microgate.com> (raw)
Fix lockup caused by 8520 serial driver not clearing
receive interrupt if flip buffer becomes full.
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
--- linux-2.6.9-rc3-mm3/drivers/serial/8250.c 2004-10-08 15:51:04.000000000 -0500
+++ bluedillo/drivers/serial/8250.c 2004-10-08 15:51:44.000000000 -0500
@@ -872,8 +872,19 @@ 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)
+ 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;
reply other threads:[~2004-10-08 21:03 UTC|newest]
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