ALSA: AACI: fix multiple IRQ claiming

Claiming the IRQ each time a playback or capture interface is opened
is wasteful; the second copy of the registered handler is identical to
the first and just wastes resources.  Track the number of opens and
only register the handler when necessary.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 17 insertions, 9 deletions

diff --git a/sound/arm/aaci.c b/sound/arm/aaci.c
index 24d3013c0231..65685afd8f77 100644
--- a/sound/arm/aaci.c
+++ b/sound/arm/aaci.c
@@ -370,7 +370,7 @@ static int __aaci_pcm_open(struct aaci *aaci,
                            struct aaci_runtime *aacirun)
 {
         struct snd_pcm_runtime *runtime = substream->runtime;
-        int ret;
+        int ret = 0;
 
         aacirun->substream = substream;
         runtime->private_data = aacirun;
@@ -391,14 +391,15 @@ static int __aaci_pcm_open(struct aaci *aaci,
          */
         runtime->hw.fifo_size = aaci->fifosize * 2;
 
-        ret = request_irq(aaci->dev->irq[0], aaci_irq, IRQF_SHARED|IRQF_DISABLED,
-                          DRIVER_NAME, aaci);
-        if (ret)
-                goto out;
-
-        return 0;
+        mutex_lock(&aaci->irq_lock);
+        if (!aaci->users++) {
+                ret = request_irq(aaci->dev->irq[0], aaci_irq,
+                           IRQF_SHARED | IRQF_DISABLED, DRIVER_NAME, aaci);
+                if (ret != 0)
+                        aaci->users--;
+        }
+        mutex_unlock(&aaci->irq_lock);
 
- out:
         return ret;
 }
 
@@ -414,7 +415,11 @@ static int aaci_pcm_close(struct snd_pcm_substream *substream)
         WARN_ON(aacirun->cr & CR_EN);
 
         aacirun->substream = NULL;
-        free_irq(aaci->dev->irq[0], aaci);
+
+        mutex_lock(&aaci->irq_lock);
+        if (!--aaci->users)
+                free_irq(aaci->dev->irq[0], aaci);
+        mutex_unlock(&aaci->irq_lock);
 
         return 0;
 }
@@ -943,6 +948,7 @@ static struct aaci * __devinit aaci_init_card(struct amba_device *dev)
 
         aaci = card->private_data;
         mutex_init(&aaci->ac97_sem);
+        mutex_init(&aaci->irq_lock);
         aaci->card = card;
         aaci->dev = dev;
 
diff --git a/sound/arm/aaci.h b/sound/arm/aaci.h
index 6a4a2eebdda1..04c4568413f4 100644
--- a/sound/arm/aaci.h
+++ b/sound/arm/aaci.h
@@ -226,6 +226,8 @@ struct aaci {
         struct snd_card         *card;
         void                    __iomem *base;
         unsigned int            fifosize;
+        unsigned int            users;
+        struct mutex            irq_lock;
 
         /* AC'97 */
         struct mutex            ac97_sem;