[PATCH v4] sdio: optimized SDIO IRQ handling for single irq

[Per Forlin]

From: Stefan Nilsson XK <stefan.xk.nils...@stericsson.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.for...@linaro.org>
Acked-by: Ulf Hansson <ulf.hans...@stericsson.com>
Reviewed-by: Nicolas Pitre <nicolas.pi...@linaro.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 d8dffc9..4910dec 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -191,6 +191,7 @@ 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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