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| author | Mike Lockwood <lockwood@google.com> | 2012-05-27 15:41:53 -0700 |
|---|---|---|
| committer | Mike Lockwood <lockwood@google.com> | 2012-05-29 16:38:46 -0700 |
| commit | 0daae7684be1f646a162b4150e7e7547550250aa (patch) | |
| tree | d6bc02400fda0e9d1b6c5813570f20db1e60a07b | |
| parent | 5df2eb9d22626c85b4fc71b0b6d55c5aa47e71d5 (diff) | |
| download | kernel_samsung_aries-0daae7684be1f646a162b4150e7e7547550250aa.zip kernel_samsung_aries-0daae7684be1f646a162b4150e7e7547550250aa.tar.gz kernel_samsung_aries-0daae7684be1f646a162b4150e7e7547550250aa.tar.bz2 | |
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.
Signed-off-by: Mike Lockwood <lockwood@google.com>
| -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 26f51a0..23a7511 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) |