diff options
| author | Mike Lockwood <lockwood@google.com> | 2012-05-27 15:41:53 -0700 |
|---|---|---|
| committer | Simone Willett <swillett@nvidia.com> | 2012-08-16 13:46:51 -0700 |
| commit | e54bf8fdf300ee603396d773c561e624e52366c1 (patch) | |
| tree | 158b79fa4498c74c35d44721386e9bd03270d28b /drivers/usb/gadget | |
| parent | bea64ae154afcbe220f2cdd0794c06dec7b9b605 (diff) | |
USB: gadget: f_audio_source: Adjust packet timing to reduce glitches
Increase max packet size and clean up timing logic so we can better
recover from not getting an interrupt in time for a SOF.
Bug 1026047
Signed-off-by: Mike Lockwood <lockwood@google.com>
(cherry picked from commit 3d2096a7959d023bc31a3cf934c3d425de01c94f)
Signed-off-by: Rakesh Bodla <rbodla@nvidia.com>
Change-Id: I0a0a6f448e71e4a0c478bb44cadc54fa021e13e4
Reviewed-on: http://git-master/r/123344
Reviewed-by: Venkat Moganty <vmoganty@nvidia.com>
Diffstat (limited to 'drivers/usb/gadget')
| -rw-r--r-- | drivers/usb/gadget/f_audio_source.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/drivers/usb/gadget/f_audio_source.c b/drivers/usb/gadget/f_audio_source.c index c7625437b517..3ba7d7569b12 100644 --- a/drivers/usb/gadget/f_audio_source.c +++ b/drivers/usb/gadget/f_audio_source.c @@ -25,11 +25,11 @@ /* Each frame is two 16 bit integers (one per channel) */ #define BYTES_PER_FRAME 4 #define FRAMES_PER_MSEC (SAMPLE_RATE / 1000) -/* Add one to FRAMES_PER_MSEC to adjust for round-off above */ -#define IN_EP_MAX_PACKET_SIZE ((FRAMES_PER_MSEC + 1) * BYTES_PER_FRAME) + +#define IN_EP_MAX_PACKET_SIZE 256 /* Number of requests to allocate */ -#define IN_EP_REQ_COUNT 16 +#define IN_EP_REQ_COUNT 4 #define AUDIO_AC_INTERFACE 0 #define AUDIO_AS_INTERFACE 1 @@ -339,13 +339,10 @@ static void audio_send(struct audio_dev *audio) runtime = audio->substream->runtime; + /* compute number of frames to send */ now = ktime_get(); msecs = ktime_to_ns(now) - ktime_to_ns(audio->start_time); do_div(msecs, 1000000); - /* Add a bit to msecs so we queue some extra requests in case - * we miss a few SOFs due to interrupts being disabled or CPU load. - */ - msecs += IN_EP_REQ_COUNT/2; frames = msecs * SAMPLE_RATE; do_div(frames, 1000); @@ -353,11 +350,15 @@ static void audio_send(struct audio_dev *audio) * If we get too far behind it is better to drop some frames than * to keep sending data too fast in an attempt to catch up. */ - if (frames - audio->frames_sent > 2 * FRAMES_PER_MSEC * IN_EP_REQ_COUNT) + if (frames - audio->frames_sent > 10 * FRAMES_PER_MSEC) audio->frames_sent = frames - FRAMES_PER_MSEC; frames -= audio->frames_sent; + /* We need to send something to keep the pipeline going */ + if (frames <= 0) + frames = FRAMES_PER_MSEC; + while (frames > 0) { req = audio_req_get(audio); if (!req) |