summaryrefslogtreecommitdiff
path: root/sound/usb/pcm.c
diff options
context:
space:
mode:
Diffstat (limited to 'sound/usb/pcm.c')
-rw-r--r--sound/usb/pcm.c106
1 files changed, 99 insertions, 7 deletions
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 769821c30031..c6593101c049 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -454,6 +454,103 @@ add_sync_ep:
}
/*
+ * Return the score of matching two audioformats.
+ * Veto the audioformat if:
+ * - It has no channels for some reason.
+ * - Requested PCM format is not supported.
+ * - Requested sample rate is not supported.
+ */
+static int match_endpoint_audioformats(struct audioformat *fp,
+ struct audioformat *match, int rate,
+ snd_pcm_format_t pcm_format)
+{
+ int i;
+ int score = 0;
+
+ if (fp->channels < 1) {
+ snd_printdd("%s: (fmt @%p) no channels\n", __func__, fp);
+ return 0;
+ }
+
+ if (!(fp->formats & (1ULL << pcm_format))) {
+ snd_printdd("%s: (fmt @%p) no match for format %d\n", __func__,
+ fp, pcm_format);
+ return 0;
+ }
+
+ for (i = 0; i < fp->nr_rates; i++) {
+ if (fp->rate_table[i] == rate) {
+ score++;
+ break;
+ }
+ }
+ if (!score) {
+ snd_printdd("%s: (fmt @%p) no match for rate %d\n", __func__,
+ fp, rate);
+ return 0;
+ }
+
+ if (fp->channels == match->channels)
+ score++;
+
+ snd_printdd("%s: (fmt @%p) score %d\n", __func__, fp, score);
+
+ return score;
+}
+
+/*
+ * Configure the sync ep using the rate and pcm format of the data ep.
+ */
+static int configure_sync_endpoint(struct snd_usb_substream *subs)
+{
+ int ret;
+ struct audioformat *fp;
+ struct audioformat *sync_fp = NULL;
+ int cur_score = 0;
+ int sync_period_bytes = subs->period_bytes;
+ struct snd_usb_substream *sync_subs =
+ &subs->stream->substream[subs->direction ^ 1];
+
+ /* Try to find the best matching audioformat. */
+ list_for_each_entry(fp, &sync_subs->fmt_list, list) {
+ int score = match_endpoint_audioformats(fp, subs->cur_audiofmt,
+ subs->cur_rate, subs->pcm_format);
+
+ if (score > cur_score) {
+ sync_fp = fp;
+ cur_score = score;
+ }
+ }
+
+ if (unlikely(sync_fp == NULL)) {
+ snd_printk(KERN_ERR "%s: no valid audioformat for sync ep %x found\n",
+ __func__, sync_subs->ep_num);
+ return -EINVAL;
+ }
+
+ /*
+ * Recalculate the period bytes if channel number differ between
+ * data and sync ep audioformat.
+ */
+ if (sync_fp->channels != subs->channels) {
+ sync_period_bytes = (subs->period_bytes / subs->channels) *
+ sync_fp->channels;
+ snd_printdd("%s: adjusted sync ep period bytes (%d -> %d)\n",
+ __func__, subs->period_bytes, sync_period_bytes);
+ }
+
+ ret = snd_usb_endpoint_set_params(subs->sync_endpoint,
+ subs->pcm_format,
+ sync_fp->channels,
+ sync_period_bytes,
+ subs->cur_rate,
+ sync_fp,
+ NULL);
+
+ return ret;
+}
+
+/*
* configure endpoint params
*
* called during initial setup and upon resume
@@ -475,13 +572,8 @@ static int configure_endpoint(struct snd_usb_substream *subs)
return ret;
if (subs->sync_endpoint)
- ret = snd_usb_endpoint_set_params(subs->sync_endpoint,
- subs->pcm_format,
- subs->channels,
- subs->period_bytes,
- subs->cur_rate,
- subs->cur_audiofmt,
- NULL);
+ ret = configure_sync_endpoint(subs);
+
return ret;
}