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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2013-09-10 at 16:19 +0100, Jan Beulich wrote:
> >>> On 10.09.13 at 17:12, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > On Tue, 2013-09-10 at 16:02 +0100, Jan Beulich wrote:
> >> >>> 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?
> > 
> > It's a hint to the compiler/reader that the return value is deliberately
> > discarded. We have a handful of these in the tree already.
> 
> And over time I managed to remove another handful...

Well, I guess I don't mind one way or another. What's the problem with
them?



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