2011/5/4 Per Forlin <per.forlin@xxxxxxxxxx>:
> 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.
>
[...]
> --- 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);
> + return 1;
> + }
[...]
The second condition can be avoided:
in process_sdio_pending_irqs():
if (card->sdio_irq_func)
call handler and return
in sdio_claim_irq():
card->func->irq_handler = ...
if (host->sdio_irqs == 1)
card->sdio_irq_func = func;
else
card->sdio_irq_func = NULL;
in sdio_release_irq():
card->sdio_irq_func = NULL;
card->func->irq_handler = ...
sdio_card_irq_put();
if (host->sdio_irqs == 1)
sdio_single_irq_set(func->card);
in struct mmc_card:
struct sdio_func *sdio_irq_func;
Best Regards,
Michał Mirosław
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