ALSA: hdspm - Enable 32 samples/period on RME RayDAT/AIO

Newer RME cards like RayDAT and AIO support 32 samples per period. This
value is encoded as {1,1,1} in the HDSP_LatencyMask bits in the control
register.

Since {1,1,1} is also the representation for 8192 samples/period on
older RME cards, we have to special case 32 samples and 32768 bytes
according to the actual card.

Signed-off-by: Adrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 20 insertions, 5 deletions

diff --git a/sound/pci/rme9652/hdspm.c b/sound/pci/rme9652/hdspm.c
index 1a52a1ae1f4c..92ac64ced29a 100644
--- a/sound/pci/rme9652/hdspm.c
+++ b/sound/pci/rme9652/hdspm.c
@@ -1323,12 +1323,27 @@ static int hdspm_set_interrupt_interval(struct hdspm *s, unsigned int frames)
 
         spin_lock_irq(&s->lock);
 
-        frames >>= 7;
-        n = 0;
-        while (frames) {
-                n++;
-                frames >>= 1;
+        if (32 == frames) {
+                /* Special case for new RME cards like RayDAT/AIO which
+                 * support period sizes of 32 samples. Since latency is
+                 * encoded in the three bits of HDSP_LatencyMask, we can only
+                 * have values from 0 .. 7. While 0 still means 64 samples and
+                 * 6 represents 4096 samples on all cards, 7 represents 8192
+                 * on older cards and 32 samples on new cards.
+                 *
+                 * In other words, period size in samples is calculated by
+                 * 2^(n+6) with n ranging from 0 .. 7.
+                 */
+                n = 7;
+        } else {
+                frames >>= 7;
+                n = 0;
+                while (frames) {
+                        n++;
+                        frames >>= 1;
+                }
         }
+
         s->control_register &= ~HDSPM_LatencyMask;
         s->control_register |= hdspm_encode_latency(n);