serial8250: too much work for irq73

Hi List

I am running into issues , when using ttyS1 on a heavy loaded application. It trys to send and recieve around 60bytes every 100ms with 57600baud. There is a PIC Microcontroller attached on the otherside which immidiatly returns the data when requested.

After some hours , the kernel starts to flood with the above messages and the system gets into an unusable state.

i am running 2.6.35.9 ( released from isee.com ) on their Igep Module ( arch igep0030).

What would you guys do ? Anything i can provide you to help here ? Its really a major issue for us and showstopping an important release.

Thanks in advance for any help or suggestion

Regards Rob

Not sure if this is the same cause, but here's some code that fixed a similar issue:

Serial: 8250.c: Clear FIFOs before enabling them

There's a short time when FIFO's are disabled and interrupts enabled between startup and set_termios.
If rx FIFO is not cleared before enabled, and there are lots of serial I/O, an interrupt indicating FIFO data error can occur.
(LSR register bit 7 set, no other error bits set).

The current interrupt handle is unable to clear this interrupt and will continue looping with a flood of "too much work" messages.

This is seen on an omap board with ST16654 type uart if a key is kept pressed in serial console while booting.

---
 drivers/serial/8250.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

index 5ed1b82..d3add25 100644
@@ -2403,6 +2403,8 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
                if (fcr & UART_FCR_ENABLE_FIFO) {
                        /* emulated UARTs (Lucent Venus 167x) need two steps */
                        serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO);
+                       serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO |
+                                   UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
                }
                serial_outp(up, UART_FCR, fcr);         /* set fcr */
        }

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