Merge "USB: gadget: f_audio_source: Adjust packet timing to reduce glitches"
diff --git a/drivers/usb/gadget/f_audio_source.c b/drivers/usb/gadget/f_audio_source.c
index cd54f0f..46cf879 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
@@ -335,13 +335,10 @@
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);
@@ -349,11 +346,15 @@
* 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)