diff options
| -rw-r--r-- | sound/usb/pcm.c | 106 |
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; } |