On Wed, 4 May 2011, Per Forlin wrote:
> On 4 May 2011 19:34, Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> wrote:
> > On Wed, 4 May 2011, Per Forlin wrote:
> >
> >> From: Stefan Nilsson XK <stefan.xk.nilsson@xxxxxxxxxxxxxx>
> >>
> >> If there is only 1 function registered it is possible to
> >> improve performance by directly calling the irq handler
> >> and avoiding the overhead of reading the CCCR registers.
> >>
> >> Signed-off-by: Per Forlin <per.forlin@xxxxxxxxxx>
> >> Acked-by: Ulf Hansson <ulf.hansson@xxxxxxxxxxxxxx>
> >> ---
> >> drivers/mmc/core/sdio_irq.c | 30 ++++++++++++++++++++++++++++++
> >> include/linux/mmc/card.h | 1 +
> >> 2 files changed, 31 insertions(+), 0 deletions(-)
> >>
> >> diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c
> >> index b300161..64c4409 100644
> >> --- a/drivers/mmc/core/sdio_irq.c
> >> +++ b/drivers/mmc/core/sdio_irq.c
> >> @@ -32,6 +32,16 @@ static int process_sdio_pending_irqs(struct mmc_card *card)
> >> int i, ret, count;
> >> unsigned char pending;
> >>
> >> + /*
> >> + * Optimization, if there is only 1 function registered
> >> + * call irq handler directly
> >> + */
> >> + if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) {
> >> + struct sdio_func *func = card->sdio_single_irq;
> >> + func->irq_handler(func);
> >
> > I think there is little point using a func variable here, especially
> > since you already reference the handler pointer in the if() statement.
> > Hence:
> >
> > if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) {
> > card->sdio_single_irq->irq_handler();
> > return 1;
> > }
> >
> What do you think about:
> + struct sdio_func *func = card->sdio_single_irq;
> +
> + /*
> + * Optimization, if there is only 1 function interrupt registered
> + * call irq handler directly
> + */
> + if (func) {
> + func->irq_handler(func);
> + return 1;
> + }
Sure, but I'd move the assignment right before the if() in that case for
clarity:
struct sdio_func *func;
/*
* Optimization, if there is only 1 function interrupt registered
* call irq handler directly
*/
func = card->sdio_single_irq;
if (func) {
func->irq_handler(func);
return 1;
}
[...]
Nicolas
