Re: [PATCH] serial: Clear proper MPSC interrupt cause bits

[Andrew Morton <akpm@linux-foundation.org>]

> On Thu, 21 Jun 2007 19:32:08 -0700 "Mark A. Greer" <mgreer@mvista.com> wrote:
> From: Jay Lubomirski <jaylubo@motorola.com>
> 
> Don't clobber the interrupt cause bits for both MPSC controllers when
> clearing the interrupt for one of them.  Just clear the one that is
> supposed to be cleared.
> 
> Signed-off-by: Jay Lubomirski <jaylubo@motorola.com>
> Acked-by: Mark A. Greer <mgreer@mvista.com>
> ---
>  drivers/serial/mpsc.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/serial/mpsc.c b/drivers/serial/mpsc.c
> index d09f209..00924fe 100644
> --- a/drivers/serial/mpsc.c
> +++ b/drivers/serial/mpsc.c
> @@ -503,7 +503,8 @@ mpsc_sdma_intr_ack(struct mpsc_port_info *pi)
>  
>  	if (pi->mirror_regs)
>  		pi->shared_regs->SDMA_INTR_CAUSE_m = 0;
> -	writel(0, pi->shared_regs->sdma_intr_base + SDMA_INTR_CAUSE);
> +	writeb(0x00, pi->shared_regs->sdma_intr_base + SDMA_INTR_CAUSE +
> +	       pi->port.line);
>  	return;
>  }

In my naive little mpscless bubbleworld, I am believing that this is a
pretty important fix, and that people in an mpscful world might want it in
2.6.22.  And even in 2.6.21.x.

But alas, that's just a guess, which was forced upon me by the lack of
suitable information in your changelog.

So please, tell us what are the real-world consequences of your patch (or
the lack of it), thanks.