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SubjectRe: [PATCH v2] sdio: optimized SDIO IRQ handling for single irq
On Wed, 4 May 2011, Per Forlin wrote:

> From: Stefan Nilsson XK <stefan.xk.nilsson@stericsson.com>
>
> 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@linaro.org>
> Acked-by: Ulf Hansson <ulf.hansson@stericsson.com>
> ---
> 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;
}
> @@ -186,6 +196,24 @@ static int sdio_card_irq_put(struct mmc_card *card)
> return 0;
> }
>
> +/* If there is only 1 function registered set sdio_single_irq */
> +static void sdio_single_irq_set(struct mmc_card *card)
> +{

The comment is slightly wrong. This should say "only 1 function
interrupt registered..." Nothing prevents this from working with
multiple functions if only one of them has claimed an interrupt.

Other than that:

Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org>


Nicolas


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