V4L/DVB (6184): cx88-alsa: Make volume control stereo

Use the balance control to make the mono volume control stereo.

Note that full range isn't supported.  The balance control attenuates one
channel by 0 to -63 dB, and the volume control provides additional attenuation
to both channels by another 0 to -63 dB.

So the channel with the most attenuation has a range of 0 to -126 dB, while
the other channel only has a range of 0 to -63 dB.  ALSA volume controls don't
appear to support this concept.  I just limited the range to 0 to -63 total.
Once you get to -63 dB, you're already at silence, so additional attenuation
is pretty much pointless anyway.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 37 insertions, 24 deletions

diff --git a/drivers/media/video/cx88/cx88-alsa.c b/drivers/media/video/cx88/cx88-alsa.c
index 85d632224f3a..25de25fb8052 100644
--- a/drivers/media/video/cx88/cx88-alsa.c
+++ b/drivers/media/video/cx88/cx88-alsa.c
@@ -552,7 +552,7 @@ static int snd_cx88_capture_volume_info(struct snd_kcontrol *kcontrol,
                                         struct snd_ctl_elem_info *info)
 {
         info->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
-        info->count = 1;
+        info->count = 2;
         info->value.integer.min = 0;
         info->value.integer.max = 0x3f;
 
@@ -565,8 +565,12 @@ static int snd_cx88_capture_volume_get(struct snd_kcontrol *kcontrol,
 {
         snd_cx88_card_t *chip = snd_kcontrol_chip(kcontrol);
         struct cx88_core *core=chip->core;
+        int vol = 0x3f - (cx_read(AUD_VOL_CTL) & 0x3f),
+            bal = cx_read(AUD_BAL_CTL);
 
-        value->value.integer.value[0] = 0x3f - (cx_read(AUD_VOL_CTL) & 0x3f);
+        value->value.integer.value[(bal & 0x40) ? 0 : 1] = vol;
+        vol -= (bal & 0x3f);
+        value->value.integer.value[(bal & 0x40) ? 1 : 0] = vol < 0 ? 0 : vol;
 
         return 0;
 }
@@ -577,19 +581,31 @@ static int snd_cx88_capture_volume_put(struct snd_kcontrol *kcontrol,
 {
         snd_cx88_card_t *chip = snd_kcontrol_chip(kcontrol);
         struct cx88_core *core=chip->core;
-        int v;
-        u32 old_control;
-
+        int v, b;
+        int changed = 0;
+        u32 old;
+
+        b = value->value.integer.value[1] - value->value.integer.value[0];
+        if (b < 0) {
+            v = 0x3f - value->value.integer.value[0];
+            b = (-b) | 0x40;
+        } else {
+            v = 0x3f - value->value.integer.value[1];
+        }
         /* Do we really know this will always be called with IRQs on? */
         spin_lock_irq(&chip->reg_lock);
-
-        old_control = 0x3f - (cx_read(AUD_VOL_CTL) & 0x3f);
-        v = 0x3f - (value->value.integer.value[0] & 0x3f);
-        cx_andor(AUD_VOL_CTL, 0x3f, v);
-
+        old = cx_read(AUD_VOL_CTL);
+        if (v != (old & 0x3f)) {
+            cx_write(AUD_VOL_CTL, (old & ~0x3f) | v);
+            changed = 1;
+        }
+        if (cx_read(AUD_BAL_CTL) != b) {
+            cx_write(AUD_BAL_CTL, b);
+            changed = 1;
+        }
         spin_unlock_irq(&chip->reg_lock);
 
-        return v != old_control;
+        return changed;
 }
 
 static struct snd_kcontrol_new snd_cx88_capture_volume = {
@@ -746,17 +762,12 @@ static int __devinit cx88_audio_initdev(struct pci_dev *pci,
                 return (err);
 
         err = snd_cx88_pcm(chip, 0, "CX88 Digital");
-
-        if (err < 0) {
-                snd_card_free(card);
-                return (err);
-        }
+        if (err < 0)
+                goto error;
 
         err = snd_ctl_add(card, snd_ctl_new1(&snd_cx88_capture_volume, chip));
-        if (err < 0) {
-                snd_card_free(card);
-                return (err);
-        }
+        if (err < 0)
+                goto error;
 
         strcpy (card->driver, "CX88x");
         sprintf(card->shortname, "Conexant CX%x", pci->device);
@@ -768,14 +779,16 @@ static int __devinit cx88_audio_initdev(struct pci_dev *pci,
                card->driver,devno);
 
         err = snd_card_register(card);
-        if (err < 0) {
-                snd_card_free(card);
-                return (err);
-        }
+        if (err < 0)
+                goto error;
         pci_set_drvdata(pci,card);
 
         devno++;
         return 0;
+
+error:
+        snd_card_free(card);
+        return err;
 }
 /*
  * ALSA destructor