Re: How to avoid serial port buffer overruns?

[Russell King <rmk+lkml@arm.linux.org.uk>]

On Thu, Aug 17, 2006 at 10:20:46AM +0100, Alan Cox wrote:
> Ar Iau, 2006-08-17 am 00:10 +0100, ysgrifennodd Russell King:
> > MIDI uses its own driver - sound/drivers/serial-u16550.c.  My guess
> 
> How peculiar
> 
> > is there's something in the system starving interrupt servicing.
> > Serial is very sensitive to that, and increases in other system
> > latencies tends to have an adverse impact on serial.
> 
> I see no support for the 16650 specific bits in the driver, so that
> alone may be a problem ?

Huh?  16550 not 16650.  Did you miss this?

        outb(UART_FCR_ENABLE_FIFO       /* Enable FIFO's (if available) */
             | UART_FCR_CLEAR_RCVR      /* Clear receiver FIFO */
             | UART_FCR_CLEAR_XMIT      /* Clear transmitter FIFO */
             | UART_FCR_TRIGGER_4       /* Set FIFO trigger at 4-bytes */
        /* NOTE: interrupt generated after T=(time)4-bytes
         * if less than UART_FCR_TRIGGER bytes received
         */
             ,uart->base + UART_FCR);   /* FIFO Control Register */

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core