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

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Message-ID: <alpine.LFD.2.00.1105041117170.24613@xanadu.home>
Date:	Wed, 4 May 2011 11:20:08 -0400 (EDT)
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	Per Forlin <per.forlin@...aro.org>
cc:	linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	lkml <linux-kernel@...r.kernel.org>, linaro-dev@...ts.linaro.org,
	Stefan Nilsson XK <stefan.xk.nilsson@...ricsson.com>,
	Ulf HANSSON <ulf.hansson@...ricsson.com>
Subject: Re: [PATCH] sdio: optimized SDIO IRQ handling for single function

On Wed, 4 May 2011, Per Forlin wrote:

> On 4 May 2011 05:40, Nicolas Pitre <nicolas.pitre@...aro.org> wrote:
> > On Tue, 3 May 2011, Per Forlin wrote:
> >
> >> From: Stefan Nilsson XK <stefan.xk.nilsson@...ricsson.com>
> >>
> >> If there is only 1 function registered, and IRQ:s are supported and
> >> currently enabled, call the callback handler directly
> >> without checking the CCCR registers.
> >>
> >> Signed-off-by: Stefan Nilsson XK <stefan.xk.nilsson@...ricsson.com>
> >> Signed-off-by: Per Forlin <per.forlin@...aro.org>
> >
> > Acked-by: Nicolas Pitre <nicolas.pitre@...aro.org>
> >
> I am working o a patch version 2 after offline discussion with Ulf Hansson.
> Instead of adding this code here.
> Add sdio_single_func member in mmc_card. Set and reset this function
> in sdio_claim_irq and sdio_release_irq.
> process_sdio_pending_irqs would only check if sdio_single_func is !=
> null and call it.

Yes, that's what I was about to propose after thinking about it some 
more.

> This will result in a bigger patch overall but the new code in
> process_sdio_pending_irqs will be minimal.

Something like this (untested) ?

diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c
index b300161..4552727 100644
--- a/drivers/mmc/core/sdio_irq.c
+++ b/drivers/mmc/core/sdio_irq.c
@@ -32,6 +32,12 @@ static int process_sdio_pending_irqs(struct mmc_card *card)
 	int i, ret, count;
 	unsigned char pending;
 
+	if (card->sdio_single_irq) {
+		struct sdio_func *func = card->sdio_single_irq;
+		func->irq_handler(func);
+		return 1;
+	}
+
 	ret = mmc_io_rw_direct(card, 0, 0, SDIO_CCCR_INTx, 0, &pending);
 	if (ret) {
 		printk(KERN_DEBUG "%s: error %d reading SDIO_CCCR_INTx\n",
@@ -166,6 +172,7 @@ static int sdio_card_irq_get(struct mmc_card *card)
 			host->sdio_irqs--;
 			return err;
 		}
+		return 1;
 	}
 
 	return 0;
@@ -183,7 +190,7 @@ static int sdio_card_irq_put(struct mmc_card *card)
 		kthread_stop(host->sdio_irq_thread);
 	}
 
-	return 0;
+	return (host->sdio_irqs == 1);
 }
 
 /**
@@ -225,8 +232,12 @@ int sdio_claim_irq(struct sdio_func *func, sdio_irq_handler_t *handler)
 
 	func->irq_handler = handler;
 	ret = sdio_card_irq_get(func->card);
-	if (ret)
+	if (ret < 0) {
 		func->irq_handler = NULL;
+	} else if (ret == 1) {
+		card->sdio_single_irq = func;
+		ret = 0;
+	}
 
 	return ret;
 }
@@ -250,7 +261,17 @@ int sdio_release_irq(struct sdio_func *func)
 
 	if (func->irq_handler) {
 		func->irq_handler = NULL;
-		sdio_card_irq_put(func->card);
+		if (sdio_card_irq_put(func->card) == 1) {
+			int i;
+			for (i = 0, i < 7; i++) {
+				if (func->card->sdio_func[i].irq_handler) {
+					func->card->sdio_single_irq =
+						func->card->sdio_func[i];
+					break;
+				}
+			}
+		} else
+			func->card->sdio_single_irq = NULL;
 	}
 
 	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..fee3df3 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 */


Nicolas
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