1 files changed, 62 insertions, 38 deletions

diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index 8818918c4237..99dae024b640 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -41,7 +41,6 @@
 #include <sound/driver.h>
 #include <linux/bitops.h>
 #include <linux/init.h>
-#include <linux/interrupt.h>
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <linux/string.h>
@@ -185,7 +184,6 @@ struct snd_usb_substream {
         unsigned int num_formats;               /* number of supported audio formats (list) */
         struct list_head fmt_list;      /* format list */
         spinlock_t lock;
-        struct tasklet_struct start_period_elapsed;     /* for start trigger */
 
         struct snd_urb_ops ops;         /* callbacks (must be filled at init) */
 };
@@ -480,6 +478,28 @@ static int retire_playback_sync_urb_hs(snd_usb_substream_t *subs,
 }
 
 /*
+ * Prepare urb for streaming before playback starts.
+ *
+ * We don't care about (or have) any data, so we just send a transfer delimiter.
+ */
+static int prepare_startup_playback_urb(snd_usb_substream_t *subs,
+                                        snd_pcm_runtime_t *runtime,
+                                        struct urb *urb)
+{
+        unsigned int i;
+        snd_urb_ctx_t *ctx = urb->context;
+
+        urb->dev = ctx->subs->dev;
+        urb->number_of_packets = subs->packs_per_ms;
+        for (i = 0; i < subs->packs_per_ms; ++i) {
+                urb->iso_frame_desc[i].offset = 0;
+                urb->iso_frame_desc[i].length = 0;
+        }
+        urb->transfer_buffer_length = 0;
+        return 0;
+}
+
+/*
  * prepare urb for playback data pipe
  *
  * Since a URB can handle only a single linear buffer, we must use double
@@ -568,12 +588,8 @@ static int prepare_playback_urb(snd_usb_substream_t *subs,
                 subs->hwptr_done -= runtime->buffer_size;
         spin_unlock_irqrestore(&subs->lock, flags);
         urb->transfer_buffer_length = offs * stride;
-        if (period_elapsed) {
-                if (likely(subs->running))
-                        snd_pcm_period_elapsed(subs->pcm_substream);
-                else
-                        tasklet_hi_schedule(&subs->start_period_elapsed);
-        }
+        if (period_elapsed)
+                snd_pcm_period_elapsed(subs->pcm_substream);
         return 0;
 }
 
@@ -588,22 +604,12 @@ static int retire_playback_urb(snd_usb_substream_t *subs,
         return 0;
 }
 
-/*
- * Delay the snd_pcm_period_elapsed() call until after the start trigger
- * callback so that we're not longer in the substream's lock.
- */
-static void start_period_elapsed(unsigned long data)
-{
-        snd_usb_substream_t *subs = (snd_usb_substream_t *)data;
-        snd_pcm_period_elapsed(subs->pcm_substream);
-}
-
 
 /*
  */
 static struct snd_urb_ops audio_urb_ops[2] = {
         {
-                .prepare =      prepare_playback_urb,
+                .prepare =      prepare_startup_playback_urb,
                 .retire =       retire_playback_urb,
                 .prepare_sync = prepare_playback_sync_urb,
                 .retire_sync =  retire_playback_sync_urb,
@@ -618,7 +624,7 @@ static struct snd_urb_ops audio_urb_ops[2] = {
 
 static struct snd_urb_ops audio_urb_ops_high_speed[2] = {
         {
-                .prepare =      prepare_playback_urb,
+                .prepare =      prepare_startup_playback_urb,
                 .retire =       retire_playback_urb,
                 .prepare_sync = prepare_playback_sync_urb_hs,
                 .retire_sync =  retire_playback_sync_urb_hs,
@@ -863,25 +869,40 @@ static snd_pcm_uframes_t snd_usb_pcm_pointer(snd_pcm_substream_t *substream)
 
 
 /*
- * start/stop substream
+ * start/stop playback substream
  */
-static int snd_usb_pcm_trigger(snd_pcm_substream_t *substream, int cmd)
+static int snd_usb_pcm_playback_trigger(snd_pcm_substream_t *substream,
+                                        int cmd)
 {
-        snd_usb_substream_t *subs = (snd_usb_substream_t *)substream->runtime->private_data;
-        int err;
+        snd_usb_substream_t *subs = substream->runtime->private_data;
 
         switch (cmd) {
         case SNDRV_PCM_TRIGGER_START:
-                err = start_urbs(subs, substream->runtime);
-                break;
+                subs->ops.prepare = prepare_playback_urb;
+                return 0;
         case SNDRV_PCM_TRIGGER_STOP:
-                err = deactivate_urbs(subs, 0, 0);
-                break;
+                return deactivate_urbs(subs, 0, 0);
         default:
-                err = -EINVAL;
-                break;
+                return -EINVAL;
+        }
+}
+
+/*
+ * start/stop capture substream
+ */
+static int snd_usb_pcm_capture_trigger(snd_pcm_substream_t *substream,
+                                       int cmd)
+{
+        snd_usb_substream_t *subs = substream->runtime->private_data;
+
+        switch (cmd) {
+        case SNDRV_PCM_TRIGGER_START:
+                return start_urbs(subs, substream->runtime);
+        case SNDRV_PCM_TRIGGER_STOP:
+                return deactivate_urbs(subs, 0, 0);
+        default:
+                return -EINVAL;
         }
-        return err < 0 ? err : 0;
 }
 
 
@@ -1413,7 +1434,7 @@ static int snd_usb_hw_free(snd_pcm_substream_t *substream)
 static int snd_usb_pcm_prepare(snd_pcm_substream_t *substream)
 {
         snd_pcm_runtime_t *runtime = substream->runtime;
-        snd_usb_substream_t *subs = (snd_usb_substream_t *)runtime->private_data;
+        snd_usb_substream_t *subs = runtime->private_data;
 
         if (! subs->cur_audiofmt) {
                 snd_printk(KERN_ERR "usbaudio: no format is specified!\n");
@@ -1433,7 +1454,13 @@ static int snd_usb_pcm_prepare(snd_pcm_substream_t *substream)
         deactivate_urbs(subs, 0, 1);
         wait_clear_urbs(subs);
 
-        return 0;
+        /* for playback, submit the URBs now; otherwise, the first hwptr_done
+         * updates for all URBs would happen at the same time when starting */
+        if (subs->direction == SNDRV_PCM_STREAM_PLAYBACK) {
+                subs->ops.prepare = prepare_startup_playback_urb;
+                return start_urbs(subs, runtime);
+        } else
+                return 0;
 }
 
 static snd_pcm_hardware_t snd_usb_playback =
@@ -1847,7 +1874,7 @@ static snd_pcm_ops_t snd_usb_playback_ops = {
         .hw_params =    snd_usb_hw_params,
         .hw_free =      snd_usb_hw_free,
         .prepare =      snd_usb_pcm_prepare,
-        .trigger =      snd_usb_pcm_trigger,
+        .trigger =      snd_usb_pcm_playback_trigger,
         .pointer =      snd_usb_pcm_pointer,
         .page =         snd_pcm_get_vmalloc_page,
 };
@@ -1859,7 +1886,7 @@ static snd_pcm_ops_t snd_usb_capture_ops = {
         .hw_params =    snd_usb_hw_params,
         .hw_free =      snd_usb_hw_free,
         .prepare =      snd_usb_pcm_prepare,
-        .trigger =      snd_usb_pcm_trigger,
+        .trigger =      snd_usb_pcm_capture_trigger,
         .pointer =      snd_usb_pcm_pointer,
         .page =         snd_pcm_get_vmalloc_page,
 };
@@ -2078,9 +2105,6 @@ static void init_substream(snd_usb_stream_t *as, int stream, struct audioformat
 
         INIT_LIST_HEAD(&subs->fmt_list);
         spin_lock_init(&subs->lock);
-        if (stream == SNDRV_PCM_STREAM_PLAYBACK)
-                tasklet_init(&subs->start_period_elapsed, start_period_elapsed,
-                             (unsigned long)subs);
 
         subs->stream = as;
         subs->direction = stream;