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authorClemens Ladisch <clemens@ladisch.de>2005-11-02 11:32:52 +0100
committerJaroslav Kysela <perex@suse.cz>2005-11-04 13:25:06 +0100
commitb55bbf06e850d7561ad7bdded1f4d8c08b1e1f11 (patch)
tree6a556b8170c354224a8c5a4400524bc59f0101db
parent091e95ee7febf894603475c44d51f8ec4fab4328 (diff)
[ALSA] usb-audio: start submitting URBs in the prepared state
Modules: USB generic driver If we submit all our URBs when a playback stream is started, the first hwptr_done update for each URB happens at the same time. This results in an underrun when there isn't enough PCM data available at this point for all URBs. To avoid this, we begin submitting our URBs earlier (when the stream is prepared), with empy packets. When the stream is started, the prepare_playback_urb() call for each URB will be run only when the respective URB has completed previously, so the first hwptr_done updates will be done nicely staggered. Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
-rw-r--r--sound/usb/usbaudio.c100
1 files changed, 62 insertions, 38 deletions
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index 8818918c423..99dae024b64 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;