mmc: sdio: optimized SDIO IRQ handling for single irq

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@linaro.org>
Acked-by: Ulf Hansson <ulf.hansson@stericsson.com>
Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 32 insertions, 1 deletions

diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c
index b3001617e67d..03ead028d2ce 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);