#define MAX_URBS 8
#define SYNC_URBS 4 /* always four urbs for sync */
#define MIN_PACKS_URB 1 /* minimum 1 packet per urb */
+#define MAX_QUEUE 24 /* try not to exceed this queue length, in ms */
struct audioformat {
struct list_head list;
/* decide how many packets to be used */
if (is_playback) {
- unsigned int minsize;
+ unsigned int minsize, maxpacks;
/* determine how small a packet can be */
minsize = (subs->freqn >> (16 - subs->datainterval))
* (frame_bits >> 3);
/* we need at least two URBs for queueing */
if (total_packs < 2 * MIN_PACKS_URB * packs_per_ms)
total_packs = 2 * MIN_PACKS_URB * packs_per_ms;
+ else {
+ /* and we don't want too long a queue either */
+ maxpacks = max((unsigned int)MAX_QUEUE, urb_packs * 2);
+ if (total_packs > maxpacks * packs_per_ms)
+ total_packs = maxpacks * packs_per_ms;
+ }
} else {
total_packs = MAX_URBS * urb_packs;
}