ALSA: AACI: make fifo variables more explanitory

Improve commenting and change fifo variable names to reflect their
meanings.

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

diff --git a/sound/arm/aaci.c b/sound/arm/aaci.c
index 393ce08b0e11d764c3b8433b2638792ac9cb8783..a148e275c80f26db21ec6668d197742fc46531d7 100644 (file)
--- a/sound/arm/aaci.c
+++ b/sound/arm/aaci.c
@@ -219,7 +219,7 @@ static void aaci_fifo_irq(struct aaci *aaci, int channel, u32 mask)
 
                ptr = aacirun->ptr;
                do {
-                       unsigned int len = aacirun->fifosz;
+                       unsigned int len = aacirun->fifo_bytes;
                        u32 val;
 
                        if (aacirun->bytes <= 0) {
@@ -279,7 +279,7 @@ static void aaci_fifo_irq(struct aaci *aaci, int channel, u32 mask)
 
                ptr = aacirun->ptr;
                do {
-                       unsigned int len = aacirun->fifosz;
+                       unsigned int len = aacirun->fifo_bytes;
                        u32 val;
 
                        if (aacirun->bytes <= 0) {
@@ -430,13 +430,11 @@ static int aaci_pcm_open(struct snd_pcm_substream *substream)
        }
 
        /*
-        * FIXME: ALSA specifies fifo_size in bytes.  If we're in normal
-        * mode, each 32-bit word contains one sample.  If we're in
-        * compact mode, each 32-bit word contains two samples, effectively
-        * halving the FIFO size.  However, we don't know for sure which
-        * we'll be using at this point.  We set this to the lower limit.
+        * ALSA wants the byte-size of the FIFOs.  As we only support
+        * 16-bit samples, this is twice the FIFO depth irrespective
+        * of whether it's in compact mode or not.
         */
-       runtime->hw.fifo_size = aaci->fifosize * 2;
+       runtime->hw.fifo_size = aaci->fifo_depth * 2;
 
        mutex_lock(&aaci->irq_lock);
        if (!aaci->users++) {
@@ -529,10 +527,13 @@ static int aaci_pcm_hw_params(struct snd_pcm_substream *substream,
                aacirun->pcm_open = err == 0;
                aacirun->cr = CR_FEN | CR_COMPACT | CR_SZ16;
                aacirun->cr |= channels_to_slotmask[channels + dbl * 2];
-               aacirun->fifosz = aaci->fifosize * 4;
 
-               if (aacirun->cr & CR_COMPACT)
-                       aacirun->fifosz >>= 1;
+               /*
+                * fifo_bytes is the number of bytes we transfer to/from
+                * the FIFO, including padding.  So that's x4.  As we're
+                * in compact mode, the FIFO is half the size.
+                */
+               aacirun->fifo_bytes = aaci->fifo_depth * 4 / 2;
        }
 
        return err;
@@ -948,6 +949,10 @@ static unsigned int __devinit aaci_size_fifo(struct aaci *aaci)
        struct aaci_runtime *aacirun = &aaci->playback;
        int i;
 
+       /*
+        * Enable the channel, but don't assign it to any slots, so
+        * it won't empty onto the AC'97 link.
+        */
        writel(CR_FEN | CR_SZ16 | CR_EN, aacirun->base + AACI_TXCR);
 
        for (i = 0; !(readl(aacirun->base + AACI_SR) & SR_TXFF) && i < 4096; i++)
@@ -964,7 +969,7 @@ static unsigned int __devinit aaci_size_fifo(struct aaci *aaci)
        writel(aaci->maincr, aaci->base + AACI_MAINCR);
 
        /*
-        * If we hit 4096, we failed.  Go back to the specified
+        * If we hit 4096 entries, we failed.  Go back to the specified
         * fifo depth.
         */
        if (i == 4096)
@@ -1029,11 +1034,12 @@ static int __devinit aaci_probe(struct amba_device *dev, struct amba_id *id)
 
        /*
         * Size the FIFOs (must be multiple of 16).
+        * This is the number of entries in the FIFO.
         */
-       aaci->fifosize = aaci_size_fifo(aaci);
-       if (aaci->fifosize & 15) {
-               printk(KERN_WARNING "AACI: fifosize = %d not supported\n",
-                      aaci->fifosize);
+       aaci->fifo_depth = aaci_size_fifo(aaci);
+       if (aaci->fifo_depth & 15) {
+               printk(KERN_WARNING "AACI: FIFO depth %d not supported\n",
+                      aaci->fifo_depth);
                ret = -ENODEV;
                goto out;
        }
@@ -1046,8 +1052,8 @@ static int __devinit aaci_probe(struct amba_device *dev, struct amba_id *id)
 
        ret = snd_card_register(aaci->card);
        if (ret == 0) {
-               dev_info(&dev->dev, "%s, fifo %d\n", aaci->card->longname,
-                        aaci->fifosize);
+               dev_info(&dev->dev, "%s\n", aaci->card->longname);
+               dev_info(&dev->dev, "FIFO %u entries\n", aaci->fifo_depth);
                amba_set_drvdata(dev, aaci->card);
                return ret;
        }

diff --git a/sound/arm/aaci.h b/sound/arm/aaci.h
index 198750d6871d51052cdd7f39a5e7db6a87d5a7e0..5791bd5bd2ab02a13730a0ef901ab709f0bb8307 100644 (file)
--- a/sound/arm/aaci.h
+++ b/sound/arm/aaci.h
@@ -219,14 +219,14 @@ struct aaci_runtime {
        void                    *end;
        void                    *ptr;
        int                     bytes;
-       unsigned int            fifosz;
+       unsigned int            fifo_bytes;
 };
 
 struct aaci {
        struct amba_device      *dev;
        struct snd_card         *card;
        void                    __iomem *base;
-       unsigned int            fifosize;
+       unsigned int            fifo_depth;
        unsigned int            users;
        struct mutex            irq_lock;