Re: [Xen-devel] [PATCH RFC 4/8] ns16550: support DesignWare 8250

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.09.13 at 16:18, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote:
> @@ -233,6 +234,16 @@ static void ns16550_setup_preirq(struct ns16550 *uart)
>      /* No interrupts. */
>      ns_write_reg(uart, UART_IER, 0);
>  
> +    if ( uart->dw_usr_bsy &&
> +         (ns_read_reg(uart, UART_IIR) & UART_IIR_BSY) == UART_IIR_BSY )
> +    {
> +        /* DesignWare 8250 detects if LCR is written while the UART is
> +         * busy and raises a "busy detect" interrupt. Read the UART
> +         * Status Register to clear this state.
> +         */
> +        (void)ns_read_reg(uart, UART_USR);

Pointless cast?

Jan


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