Re: [PATCH] serial/8250: Add support for Exar's XR17V35x family of multi-port PCIe UARTs.

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

> @@ -1484,6 +1526,7 @@ EXPORT_SYMBOL_GPL(serial8250_modem_status);
>  int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
>  {
>  	unsigned char status;
> +	unsigned char int0, int1, int2, int3;
>  	unsigned long flags;
>  	struct uart_8250_port *up =
>  		container_of(port, struct uart_8250_port, port);
> @@ -1503,6 +1546,19 @@ int serial8250_handle_irq(struct uart_port
> *port, unsigned int iir)
>  	if (status & UART_LSR_THRE)
>  		serial8250_tx_chars(up);
> 
> +	/*
> +	 * These Exar UARTs have an extra interrupt indicator that could
> +	 * fire for a few unimplemented interrupts.  Put this here just
> +	 * to be on the safe side that these interrupts don't go unhandled.
> +	 */
> +
> +	if (up->port.type == PORT_XR17V35X && status == 0) {
> +		int0 = serial_port_in(port, 0x80);
> +		int1 = serial_port_in(port, 0x81);
> +		int2 = serial_port_in(port, 0x82);
> +		int3 = serial_port_in(port, 0x83);
> +	}
> +
>  	spin_unlock_irqrestore(&port->lock, flags);
>  	return 1;

Provide your own handle_irq method rather than adding more special cases
to the default one (you can just wrap the default one and then perform
the extra actions). Just a case of trying to keep the fast paths clean and
maintainable.

Otherwise looks good.

Alan