+static int hw_rule_period_time(struct snd_pcm_hw_params *params,
+ struct snd_pcm_hw_rule *rule)
+{
+ struct snd_usb_substream *subs = rule->private;
+ struct audioformat *fp;
+ struct snd_interval *it;
+ unsigned char min_datainterval;
+ unsigned int pmin;
+ int changed;
+
+ it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_PERIOD_TIME);
+ hwc_debug("hw_rule_period_time: (%u,%u)\n", it->min, it->max);
+ min_datainterval = 0xff;
+ list_for_each_entry(fp, &subs->fmt_list, list) {
+ if (!hw_check_valid_format(subs, params, fp))
+ continue;
+ min_datainterval = min(min_datainterval, fp->datainterval);
+ }
+ if (min_datainterval == 0xff) {
+ hwc_debug(" --> get emtpy\n");
+ it->empty = 1;
+ return -EINVAL;
+ }
+ pmin = 125 * (1 << min_datainterval);
+ changed = 0;
+ if (it->min < pmin) {
+ it->min = pmin;
+ it->openmin = 0;
+ changed = 1;
+ }
+ if (snd_interval_checkempty(it)) {
+ it->empty = 1;
+ return -EINVAL;
+ }
+ hwc_debug(" --> (%u,%u) (changed = %d)\n", it->min, it->max, changed);
+ return changed;
+}
+