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

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Date:	Tue,  3 May 2011 22:51:21 +0200
From:	Per Forlin <per.forlin@...aro.org>
To:	linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linaro-dev@...ts.linaro.org
Cc:	Chris Ball <cjb@...top.org>,
	Stefan Nilsson XK <stefan.xk.nilsson@...ricsson.com>,
	Per Forlin <per.forlin@...aro.org>
Subject: [PATCH resend] sdio: optimized SDIO IRQ handling for single function

From: Stefan Nilsson XK <stefan.xk.nilsson@...ricsson.com>

If there is only 1 function registered it is possible to
improve performance by avoiding the overhead of reading the
CCCR registers and directly call the function handler.

Signed-off-by: Stefan Nilsson XK <stefan.xk.nilsson@...ricsson.com>
Signed-off-by: Per Forlin <per.forlin@...aro.org>
---
 drivers/mmc/core/sdio_irq.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c
index b300161..25291bf 100644
--- a/drivers/mmc/core/sdio_irq.c
+++ b/drivers/mmc/core/sdio_irq.c
@@ -32,6 +32,20 @@ static int process_sdio_pending_irqs(struct mmc_card *card)
 	int i, ret, count;
 	unsigned char pending;
 
+	/*
+	 * If there is only 1 function registered
+	 * call irq directly without checking the CCCR registers.
+	 */
+	if ((card->host->caps & MMC_CAP_SDIO_IRQ) &&
+	    card->host->sdio_irqs && (card->sdio_funcs == 1))
+		for (i = 0; i < SDIO_MAX_FUNCS; i++) {
+			struct sdio_func *func = card->sdio_func[i];
+			if (func && func->irq_handler) {
+				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",
-- 
1.7.4.1

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