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Subject[PATCH v2] sdio: optimized SDIO IRQ handling for single irq
Date
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);
+ 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",
@@ -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)
+{
+ 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 +255,7 @@ 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 +280,7 @@ 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 */
--
1.7.4.1


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