From 9624ea812c7afd2e403c56366cadddb9ecfb88c6 Mon Sep 17 00:00:00 2001 From: Clemens Ladisch Date: Mon, 15 Aug 2005 08:25:24 +0200 Subject: [ALSA] usb-audio: actually schedule playback URBs at frame boundaries USB generic driver Change prepare_playback_urb() not to stop preparing packets before a frame boundary has been reached. Signed-off-by: Clemens Ladisch --- sound/usb/usbaudio.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'sound') diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c index 2b4f916..3f7930c 100644 --- a/sound/usb/usbaudio.c +++ b/sound/usb/usbaudio.c @@ -164,6 +164,7 @@ struct snd_usb_substream { unsigned int curframesize; /* current packet size in frames (for capture) */ unsigned int fill_max: 1; /* fill max packet size always */ unsigned int fmt_type; /* USB audio format type (1-3) */ + unsigned int packs_per_ms; /* packets per millisecond (for playback) */ unsigned int running: 1; /* running status */ @@ -537,9 +538,13 @@ static int prepare_playback_urb(snd_usb_substream_t *subs, urb->iso_frame_desc[i].length = 0; urb->number_of_packets++; } + break; } - break; } + /* finish at the frame boundary at/after the period boundary */ + if (period_elapsed && + (i & (subs->packs_per_ms - 1)) == subs->packs_per_ms - 1) + break; } if (subs->hwptr_done + offs > runtime->buffer_size) { /* err, the transferred area goes over buffer boundary. */ @@ -907,6 +912,7 @@ static int init_substream_urbs(snd_usb_substream_t *subs, unsigned int period_by packs_per_ms = 8 >> subs->datainterval; else packs_per_ms = 1; + subs->packs_per_ms = packs_per_ms; if (is_playback) { urb_packs = nrpacks; -- cgit v1.1