[ALSA] usb-audio: factor out packet size calculation code

Modules: USB generic driver

Move the common packet size calculation code from
prepare_startup_playback_urb() and prepare_playback_urb() to a new
function.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>

1 files changed, 14 insertions, 20 deletions

diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index d5013383fad7..f5aadb001986 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -475,6 +475,18 @@ static int retire_playback_sync_urb_hs(struct snd_usb_substream *subs,
         return 0;
 }
 
+/* determine the number of frames in the next packet */
+static int snd_usb_audio_next_packet_size(struct snd_usb_substream *subs)
+{
+        if (subs->fill_max)
+                return subs->maxframesize;
+        else {
+                subs->phase = (subs->phase & 0xffff)
+                        + (subs->freqm << subs->datainterval);
+                return min(subs->phase >> 16, subs->maxframesize);
+        }
+}
+
 /*
  * Prepare urb for streaming before playback starts.
  *
@@ -492,16 +504,7 @@ static int prepare_startup_playback_urb(struct snd_usb_substream *subs,
         urb->dev = ctx->subs->dev;
         urb->number_of_packets = subs->packs_per_ms;
         for (i = 0; i < subs->packs_per_ms; ++i) {
-                /* calculate the size of a packet */
-                if (subs->fill_max)
-                        counts = subs->maxframesize; /* fixed */
-                else {
-                        subs->phase = (subs->phase & 0xffff)
-                                + (subs->freqm << subs->datainterval);
-                        counts = subs->phase >> 16;
-                        if (counts > subs->maxframesize)
-                                counts = subs->maxframesize;
-                }
+                counts = snd_usb_audio_next_packet_size(subs);
                 urb->iso_frame_desc[i].offset = offs * stride;
                 urb->iso_frame_desc[i].length = counts * stride;
                 offs += counts;
@@ -538,16 +541,7 @@ static int prepare_playback_urb(struct snd_usb_substream *subs,
         urb->number_of_packets = 0;
         spin_lock_irqsave(&subs->lock, flags);
         for (i = 0; i < ctx->packets; i++) {
-                /* calculate the size of a packet */
-                if (subs->fill_max)
-                        counts = subs->maxframesize; /* fixed */
-                else {
-                        subs->phase = (subs->phase & 0xffff)
-                                + (subs->freqm << subs->datainterval);
-                        counts = subs->phase >> 16;
-                        if (counts > subs->maxframesize)
-                                counts = subs->maxframesize;
-                }
+                counts = snd_usb_audio_next_packet_size(subs);
                 /* set up descriptor */
                 urb->iso_frame_desc[i].offset = offs * stride;
                 urb->iso_frame_desc[i].length = counts * stride;