linux-kernel - Re: [PATCH v3] sdio: optimized SDIO IRQ handling for single irq

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Date:	Tue, 10 May 2011 23:51:12 -0400
From:	Chris Ball <cjb@...top.org>
To:	Per Forlin <per.forlin@...aro.org>
Cc:	linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linaro-dev@...ts.linaro.org,
	Stefan Nilsson XK <stefan.xk.nilsson@...ricsson.com>
Subject: Re: [PATCH v3] sdio: optimized SDIO IRQ handling for single irq

Hi Per,

On Thu, May 05 2011, Per Forlin wrote:
> From: Stefan Nilsson XK <stefan.xk.nilsson@...ricsson.com>
>
> If there is only 1 function interrupt 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@...aro.org>
> Acked-by: Ulf Hansson <ulf.hansson@...ricsson.com>
> Reviewed-by: Nicolas Pitre <nicolas.pitre@...aro.org>
> ---
>  drivers/mmc/core/sdio_irq.c |   33 ++++++++++++++++++++++++++++++++-
>  include/linux/mmc/card.h    |    1 +
>  2 files changed, 33 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c
> index b300161..03ead02 100644
> --- a/drivers/mmc/core/sdio_irq.c
> +++ b/drivers/mmc/core/sdio_irq.c
> @@ -31,6 +31,17 @@ static int process_sdio_pending_irqs(struct mmc_card *card)
>  {
>  	int i, ret, count;
>  	unsigned char pending;
> +	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;
> +	}
>  
>  	ret = mmc_io_rw_direct(card, 0, 0, SDIO_CCCR_INTx, 0, &pending);
>  	if (ret) {
> @@ -42,7 +53,7 @@ static int process_sdio_pending_irqs(struct mmc_card *card)
>  	count = 0;
>  	for (i = 1; i <= 7; i++) {
>  		if (pending & (1 << i)) {
> -			struct sdio_func *func = card->sdio_func[i - 1];
> +			func = card->sdio_func[i - 1];
>  			if (!func) {
>  				printk(KERN_WARNING "%s: pending IRQ for "
>  					"non-existent function\n",
> @@ -186,6 +197,24 @@ 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)
> +{
> +	struct sdio_func *func;
> +	int i;
> +
> +	card->sdio_single_irq = NULL;
> +	if ((card->host->caps & MMC_CAP_SDIO_IRQ) &&
> +	    card->host->sdio_irqs == 1)
> +		for (i = 0; i < card->sdio_funcs; i++) {
> +		       func = card->sdio_func[i];
> +		       if (func && func->irq_handler) {
> +			       card->sdio_single_irq = func;
> +			       break;
> +		       }
> +	       }
> +}
> +
>  /**
>   *	sdio_claim_irq - claim the IRQ for a SDIO function
>   *	@func: SDIO function
> @@ -227,6 +256,7 @@ int sdio_claim_irq(struct sdio_func *func, sdio_irq_handler_t *handler)
>  	ret = sdio_card_irq_get(func->card);
>  	if (ret)
>  		func->irq_handler = NULL;
> +	sdio_single_irq_set(func->card);
>  
>  	return ret;
>  }
> @@ -251,6 +281,7 @@ int sdio_release_irq(struct sdio_func *func)
>  	if (func->irq_handler) {
>  		func->irq_handler = NULL;
>  		sdio_card_irq_put(func->card);
> +		sdio_single_irq_set(func->card);
>  	}
>  
>  	ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IENx, 0, &reg);
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index adb4888..0d64211 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -145,6 +145,7 @@ struct mmc_card {
>  	struct sdio_cccr	cccr;		/* common card info */
>  	struct sdio_cis		cis;		/* common tuple info */
>  	struct sdio_func	*sdio_func[SDIO_MAX_FUNCS]; /* SDIO functions (devices) */
> +	struct sdio_func	*sdio_single_irq; /* SDIO function when only one IRQ active */
>  	unsigned		num_info;	/* number of info strings */
>  	const char		**info;		/* info strings */
>  	struct sdio_func_tuple	*tuples;	/* unknown common tuples */

This patch doesn't apply cleanly -- please re-send against mmc-next.

Thanks,

- Chris.
-- 
Chris Ball   <cjb@...top.org>   <http://printf.net/>
One Laptop Per Child
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